75-Day Challenge When Sick: Do You Restart?

This article is for general information only and is not medical advice. Consult a doctor before starting any new fitness or diet program, and before exercising while ill.

It is Day 38. Your throat feels like sandpaper, your head is full of concrete, and you are searching for a rule that will tell you what to do.

The official program has no sick-day clause. It does not grant an exemption, and it does not publish an illness policy either. Nobody is going to decide this for you on procedural grounds.

Which means the real decision is medical, not administrative. Whether you can train safely today. What a legitimate reduced-intensity version of two 45-minute workouts looks like, if you can. And what to do with the day in your tracker if you cannot, so you do not quietly disappear from your own challenge.

This article answers all three.

Does the Program Have a Sick Day? The Official Answer

No. 75 Hard, created by Andy Frisella, documents five daily tasks and one penalty, and it carves out no exception for illness, injury, travel, or anything else. The official program page is blunt about it: if you miss a task, “It’s simple, you start over on Day 1.” The same page insists on “zero compromise and zero substitutions,” and when it takes up the question of swapping in some other task of your choosing, the answer is a flat “NO.”

Worth being precise here, because most articles are not: the official materials do not address illness at all. There is no rule saying “if you are sick, rest and restart later,” and there is no rule granting you a pass. The silence is the whole answer.

That silence is by design rather than oversight. The program is framed as a mental toughness exercise, not a periodized training plan. A training plan would have a deload protocol and an illness policy because physiology demands one. A toughness test does not, because the point is that the rules never bend.

So stop looking for the loophole. It does not exist. (If you want the full mechanics of what a restart involves and when it triggers, we covered that in the restart rules guide.)

That leaves a better question: should you train?

The Neck Check: The Rule of Thumb Athletes Use

The neck check is the heuristic most athletic trainers reach for, popularized by Randy Eichner, MD, in a 1992 Runner’s World column and echoed since by Mayo Clinic, Cleveland Clinic, and USA Triathlon. It is deliberately crude, which is why it works when you are foggy and cannot think straight.

Above the neck: runny nose, nasal congestion, sneezing, a minor sore throat, and no fever. Mild-to-moderate exercise is usually fine, and some people find it temporarily clears their congestion. Mayo Clinic still advises cutting intensity and length, with a memorable line: instead of going for a run, take a walk.

Below the neck or systemic: chest congestion, a hacking cough, an upset stomach, fever, body-wide muscle aches, or heavy fatigue. Do not exercise. Cleveland Clinic sports medicine physician Heather Rainey, MD, extends the rest list to difficulty breathing, chest tightness, nausea or vomiting, diarrhea, and any case where multiple symptoms are hitting different parts of your body at once.

Does training through a head cold make it worse? Probably not. Weidner and colleagues (1998) inoculated moderately fit adults with rhinovirus, then had one group exercise 40 minutes every other day at 70 percent of heart rate reserve for 10 days. Compared with the group that rested, there was no significant difference in symptom severity or in measured mucus weights. Moderate exercise with a real cold did not deepen the cold. It also did not fix it.

One caveat you should hold onto: the neck check is a rule of thumb, not a validated clinical protocol. It replaces guessing. It does not replace a doctor.

Passing the Neck Check: Two Workouts Without Digging the Hole Deeper

Suppose your symptoms are all above the neck and your temperature is normal. You still owe the day two 45-minute sessions, one of them outdoors. The rules govern duration, not effort, and that gap is your entire margin.

Cleveland Clinic’s guidance gives you a number to aim at: when symptoms pass the neck check, cut your workout intensity by at least half. Map that onto the two-session structure.

Indoor session (45 minutes). Restorative or gentle yoga, a mobility and stretch flow, an easy spin on a stationary bike, or a bodyweight circuit at half your normal volume. Conversational effort throughout. If you cannot hold a conversation, you are going too hard.

Outdoor session (45 minutes). A continuous walk at a purposeful pace. Continuous is the operative word: 45 minutes of actual walking, not a wander to the mailbox and back with three stops. Dress properly, because cold air on an already irritated airway sets off coughing fits for a lot of people. A scarf or buff over your mouth helps more than you would expect.

There is also a reason so many people get sick in the middle of these challenges, and it is not bad luck. Exercise and infection risk follow a J-shaped curve. In a review by Martin, Pence and Woods (2009), people getting moderate-to-vigorous activity had roughly 29 percent lower incidence of upper respiratory tract infection than less physically active people, while runners logging more than 866 miles a year had significantly higher infection risk than those under 486 miles. Two demanding sessions a day for 75 straight days sits on the wrong slope of that curve.

Watch your hydration, too. A gallon-a-day target combined with sweating, fever, vomiting, or diarrhea is a genuinely bad mix, and Rainey specifically flags dehydration and impaired temperature regulation when exercise gets stacked on top of illness. If you need the wider picture on how the program’s structure interacts with your health, our review of the evidence covers it. For a full menu of low-intensity session ideas, the rest day guide has them laid out.

When Pushing Through Is Genuinely Dangerous

Fever is the hard stop. The CDC defines fever as 100.4°F (38°C) or higher, and both Mayo Clinic and Cleveland Clinic say do not exercise with one. Not at reduced intensity. Not for a walk. Rest.

The reason is specific. Viral illness can inflame the heart muscle, a condition called myocarditis, and vigorous exercise during an active infection adds cardiac stress that may worsen that inflammation. Myocarditis is one of the recognized causes of sudden cardiac death in young athletes.

Think about what that trade actually looks like. A week off costs you a restart. Myocarditis costs you months. The American College of Cardiology describes athletes waiting 6 to 8 weeks after symptoms resolve before exercising in any capacity, followed by repeat evaluation (cardiac MRI showing resolved swelling and normal ventricular function, a symptom-limited treadmill test, and a week of ambulatory heart monitoring as they resume). A 2024 review notes that ESC guidelines and the AHA/ACC scientific statement recommend restricting exercise for 3 to 6 months after myocarditis, scaled to how long the illness lasted and what the imaging shows.

Now the move that worries me most: taking a fever reducer so the workout “counts.” You are not resolving the illness, you are hiding the single clearest signal your body has for telling you to stop. Do not do it.

See a doctor rather than training if you have chest pain or tightness, heart palpitations, shortness of breath out of proportion to your effort, fainting or near-fainting, unusual fatigue from light activity, or symptoms that run past about 10 days or get worse after seeming to improve.

As for when you can start again, CDC guidance for respiratory viruses is to return to normal activities once your symptoms are improving overall and you have gone at least 24 hours fever-free without taking fever-reducing medication, then keep up added precautions for around five days. Treat that as the earliest sensible day to attempt a real session, not the day you go back to two hard workouts.

How to Log a Modified Day Honestly

The failure mode nobody writes about is the ghost exit: you get sick, miss two days, feel like a fraud, and never open the tracker again. That is what actually ends most challenges, and it happens in silence.

You have three honest options, and each one has a real cost. Pick deliberately.

1. Modify and continue. You passed the neck check and completed both sessions at reduced intensity. Mark the day complete, note the modification, and move on. You met the requirement as written. There is nothing to apologize for.

2. Rest and restart. You failed the neck check and took genuine rest days. Under strict rules, you go back to Day 1 once you are well. Log the missed days accurately instead of backfilling them, because a record you have quietly edited is worth nothing to you later.

3. Rest and continue on modified terms. You take the rest your body is demanding and decide a streak is not worth a cardiology appointment. Switch to a gentler structure and keep the habits running. 75 Soft and other easier variants exist for exactly this.

Cleveland Clinic sports psychologist Matthew Sacco, PhD, put the case for option three well: “What actually builds resilience is having the ability to bounce back when something happens.” Being sick is a something. On a program of 150 minutes of daily training for two and a half months, it is predictable.

This is also where the tracker you use starts to matter. Reset75 has a forgiving mode that lets you skip a day without wiping the challenge, a strict mode that surfaces missed days and asks you to acknowledge them rather than letting you silently backfill, and an attempt counter so a restart adds to your history instead of deleting it. You can also build a custom challenge with lighter fitness tasks for illness weeks, swapping a 45-minute workout for yoga, stretching, or a daily step goal. Whatever you use, the point stands: track any 75-day challenge in a way that keeps telling you the truth.

Coming Back: Your First Week After Being Sick

Day one back is not two hard sessions. Use the reduced-intensity template from earlier (easy indoor work plus a continuous outdoor walk), then step the effort up over three to five days.

Watch for the relapse pattern, because it is common: you feel better, you go all-out to make up for lost time, and you are sick again within a week. That is the J-curve biting a second time, and it costs more days than the original illness did.

Rebuild the non-workout tasks first. Water, reading, diet, and the daily photo are cheap wins that restore momentum while your training capacity is still down. Keep taking progress photos even on full rest days so the timelapse stays unbroken.

For the rest of the challenge, treat sleep as your best defense and deload on purpose, before something breaks. Getting your sleep schedule right does more for your immune system than any supplement you can buy.

The Bottom Line

The program has no sick-day rule because it was never built as a training program. That is not a bug you can appeal.

So use the tools that do apply. The neck check decides whether you train. Fever is the stop sign, no exceptions and no fever reducers. Half intensity across two 45-minute sessions is a legitimate day, not a cheat.

And whichever way it goes, log it honestly. A modified day, a restart, or a deliberate pause are all recoverable. The version that is not recoverable is the one where you stop opening the app.

Frequently Asked Questions

Do you have to start over on a 75-day challenge if you get sick?

Under the official rules, yes. The program documents no exception for illness, injury, or travel, and the official materials say you start over on Day 1 if you miss any task. There is no published sick-day clause. If you would rather not lose 40 days to a virus, a forgiving-mode or custom challenge lets you take the rest you need and keep going.

Can you work out with a cold during a 75-day challenge?

Usually yes, if your symptoms are all above the neck (runny nose, congestion, sneezing, mild sore throat) and you have no fever. Mayo Clinic advises reducing intensity and duration, and Cleveland Clinic suggests cutting intensity by at least 50 percent. A 45-minute walk plus a gentle mobility session can satisfy both workout slots.

What is the neck check rule?

A sports-medicine rule of thumb popularized by Randy Eichner, MD, in 1992. If your symptoms sit above the neck, light-to-moderate exercise is generally considered fine. If they are below the neck (chest congestion, hacking cough, upset stomach) or systemic, like fever, body aches, or heavy fatigue, you rest. It is a heuristic, not a clinical protocol.

Is it dangerous to exercise with a fever?

Yes. Mayo Clinic and Cleveland Clinic both advise against exercising with a fever (100.4°F or 38°C and above). Beyond dehydration and impaired temperature regulation, viral illness can inflame the heart muscle, and myocarditis is a recognized cause of sudden cardiac death in young athletes. The American College of Cardiology describes waiting 6 to 8 weeks after symptoms resolve before any exercise at all, and ESC and AHA/ACC guidance restricts exercise for 3 to 6 months. That is far more costly than restarting a challenge.

Does working out while sick make a cold worse?

Not necessarily. In a controlled trial, participants inoculated with rhinovirus who exercised 40 minutes every other day at 70 percent of heart rate reserve showed no significant difference in symptom severity or mucus weights compared with those who rested. That finding applies to moderate exercise with a genuine head cold, not to hard training with a fever or chest symptoms.

How long should you wait to work out after being sick?

CDC guidance for respiratory viruses is to resume normal activities once your symptoms are improving overall and you have gone at least 24 hours without a fever and without fever-reducing medication, then take added precautions for about five days. Even then, ease back over 3 to 5 days rather than jumping straight to two full-intensity sessions.

What counts as a workout when you are sick on a 75-day challenge?

Any continuous 45-minute session still counts, because the rules govern time rather than intensity. A brisk 45-minute walk outdoors plus 45 minutes of restorative yoga, easy cycling, or mobility work indoors keeps both slots honest while letting your body recover.

How do you log a sick day without quitting your challenge?

Record what actually happened. If you did both sessions at reduced intensity, mark the day complete and note the modification. If you rested, log the missed day instead of backfilling it. Reset75's strict mode surfaces missed days and asks you to acknowledge them, forgiving mode lets you skip without wiping the challenge, and the attempt counter keeps your history rather than erasing it.