Limits come in many forms. At a certain point, just going longer isn't all that attractive to me, and it may not even be harder than doing the short stuff well.

Put it this way: I am 99% certain that it would be a MUCH harder challenge for me to do a sub-10 ironman (PR is 12:07) than it would be to do a double-ironman within the time cutoffs.

Plus, there's a lot of other racing stuff I like to do that doesn't require either of the above choices. Checking out different events around the country and world, blowing out my lungs at a local sprint, and continuing to race some individual sports all keep me plenty interested "beyond ironman."

When I plan to do an event, I train with a goal of doing the fastest possible time within the confines of 1) my available training time, 2) my fitness during training and on race day. So when I try to do an IM as fast as I can, I AM pushing my limits. But the same goes for a good hard 5k.

If you choose to do it that way, all racing is pushing your limits.

I agree with the above sentiments. For me pushing the limits can be a test against time or distance (or both). It may also be involve another person, who may push me harder than I can push myself.

I race to train… that is, I always need to have a race on the horizon to keep me in training mode. If I don't have a race out there—even if it's 10 months away—I find it too easy to stop training. It's a good way to approach success in life in general. Set a goal—make sure it's stated in such a way that it's measurable so you can know when you've reached it. When you reach that goal, set another.

So for me, I guess it's more about consistent improvement than pushing limits. But if you keep setting goals, keep accomplishing new things, keep growing, don't settle—you'll be pushing limits all your life.

As a younger racer I would encourage you to focus on speed, technique, and fun. There is plenty of time to focus on distance and endurance. I'd hate to see someone with such an early passion for the sport burn out or become injured from going too far while your body is still growing.

Ever wonder why the USAT keeps race distances short for the juniors? Or why high school cross-country is usually competed in the 5K?

Do you really need to go long to push your limits? A sprint or Oly at or near LT with legs and lungs rebelling is pretty dang challenging. And just because you FINISH a distance, doesn't mean you met it's challenge. You can ALWAYS go faster and harder. That's the beauty of triathlon- there is plenty of poison from which you can pick.