The summer after I turned eighteen, I was hiking in the Alps with my mother when she formally introduced me to a glacier; and then we rummaged in its morraines, its till, and we brought home handfuls of garnets. And I decided that in addition to chemistry, I was definitely going to take geology, and that just left me to choose between physics and materials science as my third option.
(After a certain amount of tears and a lot of people pushing me towards physics, I ended up in MatSci and actually mostly really enjoyed it.)
-- and as it turns out: while I still love chemistry and I especially love total organic synthesis (I am really good at organic chemistry; and I want to qualify that statement by pointing out that if you've been hanging around here for any time at all you've probably noticed how massively insecure I am about my capabilities in general), I also really like rocks.
There's an alternate-universe me, though, who decided that essays were too difficult and rocks were too challenging; who decided to play it safe and stick with the thing I knew I could excel at. Alternate-universe me might be doing a PhD, but there's also a high chance they'd be contemplating working in R&D for a big pharma company, because we the both of us consider chemical industry less outright evil than oil & mining.
And if not that... well, my current big question is whether to stay in academia or train as a counsellor. I like rummaging in people's heads and finding out how things slot together; I like improving my understandings of how my own head works. I think I consider helping people to sort out their brains very similar to teaching my undergraduates - it all boils down, for me, to giving people tools and encouraging them to work out how to apply them most effectively. And would I want to do research as well as practice? Well, probably, because I seem to be - in many respects - be An Academic; but those are the paths I've had mapped out, at one time or another.
(The positive ones, at any rate. I've walked the valley of the shadow of death, too; but I don't particularly feel moved to share that cartography.)