Dude, I feel the same as you.
I've just turned 18 and really love MMA, I've been looking around for some places to learn. There is a very good Muay Thai school near me (well I say near me, it's 40 mins away) and about an hour away there is a pretty good looking club that does BJJ, Wrestling, MMA and Submission Wrestling.
I do strength and cardio training most days, it's just persuading my parents to take me there at least once a week, until I can pass my driving test, then I could go more often.
I don't think age is a problem though, we're still young and can easily become proficient fighters if we are meant to do so, I'm a big believer of natural talent, which I'm hoping I have. I've never seen myself doing a conventional job so who knows!