When we promise ourselves we will do something, these promises don’t have much meaning to us. However, if we promise someone else that we are going to do something, then our pride is at stake. If we break our promise, we will look unreliable, and we will feel bad about ourselves. Other people may stop trusting us.
That’s why having an accountability partner is so powerful. It’s enough if your friend is helping you to achieve your goals. If you’re looking for something much stronger, something that will truly force you to follow your habits, you can write up an agreement. Yes, a formal-looking agreement, with some punishment in case you don’t follow your new habit. For example, you pay your friend $20 each time you skip the gym.