Yes, of course. If we're unhappy with something about us why shouldn't we change it?
Then theres general cosmetic surgery, thats up to us if we have it or not, if you dont like it then why not change it? You can.
And finally, personality, it's like. If you're shy, but you dont like that, then you can try to be confident. I personally am shy in new situations but I'm going to try and be more confident, because I dont like being shy.
So all in all I think that if you're unhappy with yourself and are able to change it, do it, dont live your life not liking it.