Acting. It's a profession. Pretending to be someone else. Acting "as if." It can be liberating. Taking on another persona.
It's also one of those "recovery"ideas. "Fake it till you Make it:" imitating confidence, competence, and an optimistic mindset, a person can realize those qualities in their real life.
Act like the thing you want to be. Of course, like everything, it has its limits. If you walk around acting like Napoleon they will probably put you away somewhere, feed you drugs, try to get you "back to reality."
Not feeling it? Act like you do feel it. Who knows, maybe you will feel it?