Jeff Wise for Psychology Today:

'The most effective way to move toward change is to act like you’ve already achieved it. Don’t worry about playing mind-games with yourself. Don’t worry about affirmations. The way to become a fit person is to act like one. I’ve always found that the hardest part of exercising—the only hard part, really—is putting on my sneakers. Once they’re on, there’s pretty much a 100 percent chance of getting some form of workout done. Why else would I have these shoes on?

Obviously, you can’t change your internal reality overnight. But act out the change you want, and day by day, the weight of evidence will become undeniable. Before long, the person you pretend to be becomes the person that you are. In one experiment, researchers recruited subjects who said they wanted to learn one new habit, and asked them perform the new behaviour every day. After 60 days, most of them rated the newly learned habit as effortless to perform. What had once been a desired change was now an accepted reality.