The original thread was posted by Marcellahearts in the MtF transsexual board in February, and I thought, "Hey, this is a great idea, why not open it up to a general theme?"
So, I'm not trying to steal your idea, I guess I'm just expanding it to the whole community. This isn't just trans-related - if you could go back and tell yourself anything or give yourself any advice, what would it be?
I find myself thinking about this all the time, that's kind of why I really wanted to reply to the original thread but felt like I'd be invading that discussion

I probably wouldn't even tell myself I'd end up being trans, I figure I'd realize that anyway since I'd be me as a guy going back to talk to me as a girl.
What I would say is to quit being a fat lazy p.o.s and get into shape - not for others to approve of me, but to just be healthy and happy, and that way maybe I wouldn't have started SI and contemplating suicide. I'd also tell myself to try and get my mom to quit smoking ASAP, and possibly save her life. No idea when she started developing cancer but it was at least a few years before she was diagnosed...
Oooh and, I'd tell myself that if (when) I meet a guy names Andrew R, to kick him in the balls and not date him. ^.^