How do I know what career is for me?

I'm a HS senior trying to figure our what type of career I want after college. I'm already finished with college apps (attending columbia/penn/duke/uchicago), and I'm starting to think of generally what I want to do after college. The most common piece of advice I've gotten is "start early or you will be left behind." I know other kids at my school already preparing for IB technicals. The problem is, though, I don't know what type of career I want. I'm considering IB (tons of buy-side exit opps) and quant trading (enjoy applied math/CS, also better hours/pay). I've done my research on both careers, but I don't feel like I'll ever know what's right for me until I do it. I don't want to 'choose wrong' as I heard QT and IB have no overlap and I can't lateral over from one to another (especially since QT is very technical heavy). I've also heard a lot of people say that they wish they never did IB -> buy-side because the hours will suck for a long time, which makes it a strenuous job, no matter how much they like what they do.