There's nothing wrong with redefining yourself often and radically. It's your personal version of species evolution: you're exploring the possibility space of your own being. You're tweaking the programming, hacking the algorithm whose solution equals 'you.' You have no idea what your limits are, or indeed if you even have any, until you push yourself out of your self-imposed boundaries.
This is, of course, challenging when considering friends, family, and other social and economic obligations. If you're happy right now - truly and honestly happy when you look inside yourself - then perhaps don't bother. Why spoil a good thing, right? But if you have even an inkling of suspicion that you're not living at your full potential, take the necessary steps to work on that. Do new things, step outside your usual environment, meet new people. Open the window and tell life: I'm ready for more.
And life will answer.