Perhaps it is indicative of my age.  Perhaps my generation.  But as I age, most of my athletic endeavors tend to be solitary (...as opposed to team-oriented).
Heck, most of my endeavors, ...period. 
While this phenomenon has not escaped my notice, it troubles me very little.

I spent much of my youth involved with various team sports. Baseball.  Football.  Even Hockey. Yet to organize a game with my contemporaries today would, quite probably, require the social scheduling skills of Martha Stewart (assuming that I could coax enough of them out of their Lazy-Boys to form a quorum).   While I still occasionally coach, much of my athletic activities are done far away from others.

Running is solitary.  Swimming is solitary.  Even biking hinders any type of true camaraderie.  I'm okay with this.
In many ways, I welcome the solitude, the alone-ness.  As I utilize my physical body to its limits (...or as close as this mortal shell will allow), my mind is set free to explore its own frontiers.  "To boldly go..."
I talk to myself, I argue with myself, I write.  Or, as my wife explains it: "I hear music that no one else can hear."

I assume that it is similar for many within my age-group.  Additionally, however, there is the beauty of finding a limit (...however humble) and pushing past it... only to find a new limit.
I have spent no little time and effort (for more than a decade) exploring how the human animal reacts to apparent "limits," (both physical and mental) ...and how the irreverent few manage to push beyond those limits and achieve "the impossible."  Triathletes.  Navy Seals.  Academics.  The physically impaired.

In my studies, I continually return to the truism that often, someone will do something difficult or impossible simply because it is expected.  Or, more often, because we assume that others have already gone before us.

In speaking with Triathletes in particular, I continually run into the story of Julie Moss.

In 1982, Julie was a Grad Student in Southern California. She was working on her Exercise Physiology thesis. As part of her research, she whimsically signed up for the fledgling Ironman Triathlon in Hawaii.  Despite all expectations, she was surprisingly competitive and was leading the race into the final few miles of the marathon.
But with two miles remaining in the race, the wheels fell off.
Julie had misjudged her caloric requirements and her body literally broke down. Her brain could no longer answer her commands and she staggered awkwardly, still stumbling towards the finish line.  Initially she staggered, then fell, only to rise slowly on wobbly legs and stumble again, eventually losing control of her speech as well as her bowels.  But she wouldn't stop.
Julie would collapse, rise, collapse, run 20 feet and collapse again.
All of this was captured by ABC's Wide World of Sports and as Julie literally crawled across the finish line, the sport was transformed from obscure, quirky outlier to a cult.
I can remember sitting alone, watching this passion-play unfold on television.  Aging alterboy that I am, I can remember thinking "Julie falls the third time..."   and thinking that no one "gets this" but me.

How wrong I was.
The next day, it seemed that everyone had seen the event.  Julie (who, incidentally, finished 2nd to Kathleen McCartney) became an overnight celebrity. Completely inadvertently, she had become the symbol for a generation emerging from Jimmy Carter's "malaise" into "Morning in America."  This was still a country of champions.   A place where accomplishment came only after effort, only after a price had been paid; but a place where greatness was still the norm.

Interestingly, Julie went on to demi-fame.   She eventually married (probably the greatest Triathlete of all time) Mark Allen.  (There is some discussion that their children should be declared ineligible from competition due to unfair genetic advantage.)
However, Julie's lasting claim-to-fame may be that she was one of the original spokesmen (...women?) for a fledgling shoe company called Nike.  Julie sat on a couch and recited a number of ways to get into better physical condition; "Just run, just swim, just jump, just skate, etc. etc..."
However, after the screen had faded to black, Julie's face popped up one more time and she uttered the 3 words that have built an empire; "Just DO It!"

Today, there is an entire subset of triathletes that mark their fascination with the sport as starting on that day in 1982,  ...and a woman that showed what true accomplishment looks like.