I was a runner first, took up biking, did duathlons and then a couple of crits (scared of the crashes) and now am picking up swimming and the goal is to do a few sprint tri's next year. I like biking a lot more than running but I can run a lot faster than I can bike. Its also easier to get an intense workout running than biking in a shorter time, I find. the impact on the body might have something to do with it I guess.

Oh and I sucked at running, duathlons, crits and I expect to suck at triathlons too. At least its on your own terms and you dont get dropped by anyone. Thats the only saving grace.