Change becomes easier when you actively involve your environment. By involving others in your goals you activate the psychological principle of Commitment and Consistency; the need for our behavior to be consistent with what we want, think, or say.
In prehistoric times, you depended on the group for survival. As a result, our brain has developed some basic principles that are completely focused on promoting social acceptance and preventing rejection. Commitment and Consistency is an example of a basic principle. It prevents others from seeing you as unreliable. So when you make concrete agreements about how you want to change something or achieve a goal, the chances are that you will actually achieve those goals.
So do you want to get fitter? Then a subscription to the gym is a good starting point. But your chances of success increase even more by telling your friends or co-workers that you’re going to work out every Monday and Wednesday. They’ll ask you the next day if you did actually go and this way you you will and have to go, right?
Source: Cialdini, Influence