Can anxiety be a personality trait, and if so, is treating it turning one's back on oneself?

I never realized anxiety was such a problem for me until I didn’t have it anymore. Now that I’m on an antidepressant I feel like a whole new person. Mostly in a good way.

I’m a lot happier now, I don’t get nearly so nervous and I don’t dwell on negatives as much. I’m also less driven (I don’t put in the same kind of effort into my classes anymore now that I’m not wracked with terrible fear of failure) and more apt to settle for mediocrity.

I like being happier, but the old me didn’t value happiness so much as she valued the idea that I could make a positive impact on the world. The old me would shake her head at the state of my priorities these days.

Personal advice as well as general philosophical pondering is welcome. xD