I'm not sure my younger self would have listened to me honestly... I wasn't one to like taking advice much when I was young and always seemed to take my own path.

I would probably encourage myself to run a little bit more, or at least keep a pace of jogging.

The folks you describe, tinmann0715, are what we refer to as "Pioneers" and, as we know, while Pioneers blaze the trails, they also take the arrows and lose their scalps. So, is it better to be an innovator or an imitator?  Uber started the ride-share phenomenon but now they are in trouble, and there is a plethora of "imitators" all doing the same thing.  My point is that while we Americans tend to be a "Shoot-first-and-ask-questions-later" society, I believe that to be a small percentage of our culture; that we really do have others' best interests at heart. (OK, with the exception of our current political administration) 

And there's no irony that you should mention risk, too, Peter; there are those who are deathly afraid of flying but it has been proven that flying is a safer mode of transportation than driving.  And there is risk when one just gets out of bed in the morning: Will I get hit by a bus today?  Will I trip and fall and break my leg today?  Will I contract some flesh-eating virus today?  I mean, OMG!  We all just need to stay at home, curl up and die!

Now, I say that last piece a little "tongue-in-cheek" and I am not intending to patronize or belittle anyone with a phobia, as I know those fears appear real to those folks who suffer.  I, personally, still suffer from arachniphobia and my wife is constantly "saving me" from spiders.  But as the old 80's workout video saying goes, "No Pain, No Gain!"  You are correct in that we need to move beyond our "comfort zone", or at least stretch it considerably, in order to achieve the things we want in life.  Where would we be if we never took the risk of learning to crawl, or walk, or run?  We'd still be sitting on the floor, in our room, in the house in which we were born!  Not a pretty picture for me, at least!

Now over to all of you: if you had the chance to pass on advice to your younger self, knowing that if you did there was a chance it would change who you are today, would you do it?

This question presents an interesting conundrum and, as folks have mentioned, it's all hypothetical anyway, but I would have to say no; that I would not pass on advice to my younger self, were I actually given an opportunity to do so.  Why?  Because I love my life now, and while I might have changed some of the outcomes, I would not wish for a "Sliding Door" that propelled me into a different timeline.  There is a song by Garth Brooks called "The Dance" and in it, he looks back on a love now lost, and has a melancholy, yet poignant, commentary:

"And I, I'm glad I didn't know

The way it all would end, the way it all would go

My life is better left to chance

I could've missed the pain but I'd've had to miss The Dance"

Everything happens for a reason, as someone mentioned in another thread, and I totally believe that.  Yes, I could've missed some pain but I cannot imagine being anywhere else, with anyone else, at any time else. (Wait, what? ;-)

I don't know whether I would give advice (or whether younger me would believe it), given the chance - 'all has led to this moment', after all But it is really interesting reading this thread to see the great advice others have offered!