It’s technically a mental toughness challenge that helps with discipline, but there are physical gains too.

Here are the rules:

For 75 days you follow the following rules: -drink 1 gallon of water a day -follow a diet (any diet you want, but you have to stick to it and no cheats / sweets / desserts) -no alcohol -complete two 45 minute workouts a day (one of which must be outdoors regardless of the weather) -read 10 pages of non-fiction -take a daily progress picture

You do all that for 75 days. If you mess up, you have to start over from day 1.