75 Hard vs 75 Soft vs a 66-Day Challenge: Which Should You Do?

75 Hard, 75 Soft and the 66-day challenge all promise the same thing: show up every day for a couple of months and come out different. They ask for very different amounts.

The short version: 75 Hard is a strict, all-or-nothing program with five daily tasks and a restart rule. 75 Soft is a gentler version of the same idea. A 66-day challenge is one habit of your choice, kept for 66 days. Here is how they compare, and how to pick.

The 75 Hard rules

75 Hard was created by entrepreneur and motivational speaker Andy Frisella and launched in 2019 (Cleveland Clinic). For 75 days in a row, every day, you:

1. Follow a diet of your choice, with no cheat meals and no alcohol.
2. Do two 45-minute workouts, at least one of them outdoors. Cleveland Clinic's summary says the two should be three hours apart.
3. Drink a gallon of water (about 3.8 liters).
4. Read 10 pages of a nonfiction book. Audiobooks don't count.
5. Take a progress picture.

Miss any task on any day, and you start again from Day 1.

The 75 Soft rules

75 Soft is an unofficial, gentler version that spread on TikTok, credited to user Stephen Gallagher (Marathon Handbook). For 75 days, you:

1. Eat well, and drink alcohol only on social occasions.
2. Work out for 45 minutes a day, with one day a week for active recovery like yoga, stretching or a walk.
3. Drink 3 liters of water.
4. Read 10 pages of any book.

Many versions add a photo on Day 1 and Day 75 (WebMD). Most importantly, a missed task does not send you back to Day 1.

The 66-day challenge rules

The 66-day challenge is simpler still. You:

1. Pick one promise and write it as a sentence: "I promise that I will walk for 30 minutes."
2. Set a floor: the smallest version that counts on a bad day.
3. Take one photo every day you keep it, as proof.
4. Never miss twice. One miss is allowed; two in a row is not.
5. Check in on Day 22, 44 and 66.

Why 66 days? It was the median time to form a new habit in a study at University College London, with a range of 18 to 254 days (Lally et al., 2010). The same study found that missing one day did not materially affect the process, which is why the challenge allows a single miss. The full rules and a free printable are in The 66-day challenge.

75 Hard vs 75 Soft vs 66 days, side by side

	75 Hard	75 Soft	66-day challenge
Length	75 days	75 days	66 days
Daily tasks	5	4	1 (your choice)
Exercise	Two 45-minute workouts, one outdoors	One 45-minute workout, one active recovery day a week	Only if your promise is exercise
Diet	A diet plan, no cheat meals, no alcohol	Eat well, alcohol only on social occasions	Only if your promise is about food
Water	1 gallon (about 3.8 liters)	3 liters	Not required
Reading	10 pages of nonfiction, no audiobooks	10 pages of any book	Not required
Photos	A progress picture every day	Often Day 1 and Day 75	One proof photo every day
Missed a day	Restart from Day 1	Keep going	Keep going, but never miss twice
Best for	People who want a total, short-term overhaul and have the time	People who want structure without the extremes	People who want one habit to stick for good

Which one should you do?

Choose 75 Hard if you want a short, all-in reset, you have at least 90 minutes a day for workouts plus time for the rest, and the restart rule motivates you rather than scares you. Its strictness is the point.

Choose 75 Soft if you like the idea of training, eating better, hydrating and reading together, but need room for a normal life: a rest day, a dinner with friends, a missed task without starting over.

Choose a 66-day challenge if there is one specific habit you want to keep long after the challenge ends, or if you have tried a 75 before and stopped. One promise is much easier to fit around work, kids, travel and bad weeks.

You can also stack them: run a 66-day challenge on the habit you care about most, and add more once it runs on its own.

A note on safety

Two workouts a day, a gallon of water and a strict diet is a lot for many bodies. If you have a health condition, are pregnant, are new to exercise or have a history of disordered eating, talk to a doctor before starting a program like 75 Hard. Cleveland Clinic's overview covers the risks.

How to track any of them with one photo a day

All three get easier when each day leaves proof. 75 Hard already requires a daily progress picture; a 66-day challenge is built around one.

• For 75 Hard or 75 Soft, take one photo a day that shows the day was done: your outdoor workout, your empty water bottle, the open book. Or log each rule as its own habit.
• For a 66-day challenge, your one promise gets one photo a day.
• On the last day, put Day 1 next to the final day with our before and after maker, or turn every day into a short film. Our guide to tracking a 75-day challenge with a daily photo covers the setup.

In Safar, each rule or habit becomes a promise. Each day you keep it, you log one photo or short video, stamped with its day number. Every promise keeps its own streak, all your proofs sit on one wall, and at the end you pick a date range and a style and Safar builds the reel.

Questions

Is 75 Soft easier than 75 Hard?

Yes. It has one workout a day instead of two, a rest day each week, less water, any book instead of nonfiction, and no restart after a missed task.

Can I do 66 days instead of 75?

Yes. Sixty-six days is the median time to form a habit in the UCL study, so it is a well-grounded length if your goal is one habit that lasts. It is your challenge; 75 is not a magic number either.

What happens if I miss a day?

In 75 Hard you restart from Day 1. In 75 Soft you keep going. In the 66-day challenge you keep going, but make the next day non-negotiable, because two misses in a row is how challenges end.

Do I need an app?

No. A notebook or a printable tracker works. An app helps if you want photo proof, a day count and a video at the end without doing it by hand.

"75 Hard" is a program created by Andy Frisella. "75 Soft" is an unofficial variation. Safar is not affiliated with either.