On the subject of turning 19, what advice would you give to your 19-year-old self

all of those people who are doing things you want to do feel the same way about it as you. 

aside from very few things (you can count on one hand), nobody really knows what they're doing & is making it up as they go.

you won't know unless you try & it's better to try & fail than to regret never starting.

Evangelizing Incentives That Combine Self Interest With Collective Benefit & A Few Other Things I'm Still Trying To Figure Out