As Lise said, enjoy your ability to swim well -- some of us really envy that ability. Good luck with the running -- it WILL get better.
I envy every person who can actually run more than 200 yards at a time.

Gosh, I see people who look pretty unfit (not just triathletes, generally speaking when I see people running)... and they can run.

And it has to be hard on their joints... but they are doing it... WHY can't I? WHY? It just seems so unfair that my body won't let me run.

I know you can't judge an athlete by his/her cover... but gosh... it's really frustrating that others can run and I can't.