Going to the gym to lift the weights because you’re not strong.
Going to the gym to lift the weights because you’ve decided that you’re the kind of person who goes to the gym to stay active.
Is this faking it till you’ve made it?
No, because you’ve already made it by deciding to have the kind of habits you need to have to be the kind of person you want to be. The important part is not just saying you’re that kind of person but doing what that kind of person would do.