Two years ago I decided I was a healthy person. Since I was a healthy person, I started eating like one and lost 30 pounds in 6 weeks.
Shortly after that, I decided I was an athlete. Since I was an athlete I started working out with professional MMA fighters and now I compete in Jiu Jitsu tournaments.
Back in college, I decided I was a good student. Since I was a good student, I got straight A’s and a full ride scholarship, rather than the B’s and C’s I got in high school. (Then I decided I was a rock star and dropped out of college to tour with my band for 7 years).
More recently, I decided I’m good at Math and now I’m a Computer Science major (after avoiding Math classes for 13 years).
I think a lot of people say things like "I want to be healthier," "I wish I were an athlete," or "I would like to be a good student." I say decide what you are and be it.