Thanks! I love my finisher's medals. Tangible evidence.
Anybody can do this. A couple years ago I couldn't so much as walk around the block, let alone run, or bike, or swim. It just takes some training, one small step at a time. And sometimes it is a psychological challenge more than anything. Lots of people are genuinely afraid of swimming, and I was terrified of crashing on the bike. These too are overcome one step at a time.
The thing that really astonished me when I started doing this, is that people of all shapes and sizes really do this crazy sport. I always thought it was for the uberfit crowd, but larger people do race triathlon, and they do it respectably. Everyone is very supportive too--it tends to be a very welcoming community. Runners are good too, but it tends to be a larger community and I don't generally get to know people there as well just because of the number of people involved.
One warning, I re-experienced this morning. The day after a race, weight tends to jump a few pounds (verified this with a bunch of other triathletes and runners). With the hydration balance issues--heavy sweating and overcompensation, swelling sore muscles, extra food taken in for energy and recovery, and a digestive system that's a bit off, I'm usually up by 2-4 pounds.

I had to talk myself down very calmly off the scale this morning. It goes away in a day or two, but is sort of shocking the first time it happens. If you have a body fat scale, you'll see it's on the low side as well, since that measurement is also affected by hydration issues.
Anne