Ah, happiness, that elusive state. Philosophers, theologians, psychologists, even economists, have long sought to define it, and since the 1990s, a whole branch of psychology—positive psychology—has been dedicated to pinning it down and propagating it.
Most of us wish we could improve certain things about ourselves. Lasting change is difficult: Many of our habits are deeply ingrained, and certain core personality attributes may be immutable. But even the oldest of habits and character traits can be altered to varying degrees, as it's never too late to change; with effort and determination, it is possible to be the person you want to be.