I would agree with jt.
However, and you knew it was coming because you made a reference to it, you will be competing with people who have a single minded UNQUENCHABLE BURNING DESIRE to do it.
I wouldn't be put off by little setbacks (believe me, when you look back they will seem little) like age and flunked degrees - getting in is (IMHO) more to do with drive and raw potential (oh, and luck).
Never give up,
Ray ;-)