My wife's uncle had a successful if unassuming career as a civil engineer. Then one day, shortly after his 50th birthday, he decided that he never really wanted to be a civil engineer and that his real passion was social anthropology. By 62 he had a PhD in social anthropology, 3 or 4 published books in the field, was generally considered an authority in his niche and split his time between writing and lecturing part time at the university. He worked until he was 70 and enjoyed every minute of it far more than his previous career. Even at 50 it's not unreasonable to assume that you have anywhere from 25-50% of your working life ahead of you, don't let a decision you made as a kid get in the way of getting the most out of those years.