The theory of relativity.

What defines someone as having achieved greatness? Is it winning the Western States 100, one of the most renowned ultra marathons in the country, seven consecutive years? Is it running 50 marathons in 50 days? Still not impressed? How about running from California to Key West? While I find each of these seemingly super-human feats of athletic prowess awe-inspiring, is it the mere act that makes each of these runner great? I think we can all concede that Scott Jurek, Dean Karnazes, and John Pyle are great runners. And if you don't know these names, google them. I'll wait.

Ok. Since you obviously now agree with me, we can continue.

To someone who runs 30 miles as a warm up, is running 100 all that extraordinary? Not really. Now, I am by no means implying that running 100 miles isn't special, but isn't that 100 mile run equatable to a 5k for someone who has never been a runner? Unequivocally, yes. I find the non-runner who decides to do a couch to 5k program as equally motivational as a Scott Jurek. Running 50 miles is relatively easy when you've already ran one. It's that first mile that's the challenge. This weekend, I ran in an 11 mile mud-filled obstacle race called Tough Mudder with my husband and some friends. My brother-in-law kept pace with a few of us self-proclaimed endurance junkies, only to find out around mile 8 that the furthest he had previously ran was about a mile or so (he wasn't really sure). Our other friend had never done anything like it before either. And he's a big guy, making the course more challenging. His tenacity made the spectators and other competitors take note. By the end of the race, random strangers were coming up to him and shaking his hand, telling him how inspiring he was. I am so blessed to have people like these in my life.

The part that I find most encouraging about the greats of our sport is that many of them find their stride later in life, usually due to a midlife crisis or the like. They don't have some storied carrier of racing dating back to their prepubescent years. For example, after leading a sedentary life of pizza and potato chips, Dean Karnazes simply opened his front door and decided to run. Something just clicked and he changed his life. And this story repeats its self countless time in the endurance sports world.

So, what's the moral of the story? Greatness is relative, and the capacity for greatness lies in all of us. How will you be great?