The 75 Hard Challenge by Andy Frisella was created as a mental toughness challenge.
This challenge consists of 6 rules being:
This is not meant to be another internet challenge. It is not a fitness challenge. There are obviously going to be some physical changes, but this is a mental toughness challenge.
Over the next 75 days you will be building skills like discipline, endurance, grit, fortitude, perseverance, & beliefs in yourself to succeed.
But don't listen to me, hear it from the creator himself.
75 Hard | The 75-Day Tactical Guide to Winning the War with Yourself