I'm surprised at the pushback to this post. I've always assumed a lot of runners felt this way. I was a good basketball player in high school, and loved the sport. But I was a great runner, so that's what I pursued in college and beyond. How many 13-year-olds out there actually fantasize about the Trial of Miles?
There are lots of things I enjoyed about serious running, especially the camaraderie, but also the travel, and the adventure, and yes, the winning (not that I won many races once I moved up to higher levels, so let's say... the possibility of winning). But enjoying the actual act of running in the same way that I enjoyed shooting hoops? Not really.
After college, I had my first serious injury, which kept me from running for over a year. At that point, I discovered (to my surprise) that I really missed it. But again, I think what I missed most was the feeling of being a big-time athlete, of being fully immersed and dedicated to something, not the actual running.
The irony of all this is that now, in my late 40s, I still train, do one or two hard workouts a week, and race a few times a year. I've come to enjoy the process, and I enjoy being fit, even if I still don't enjoy racing and don't particularly love training. It's hard to explain. One of the posters above mentioned what a privilege it is to be really good at something. I agree with that, and it keeps drawing me back. I play pick-up hoops, and rock-climb, and play a musical instrument, and I enjoy all those things even if I'm doing them alone. But I can show up at a random road race on any given Sunday and beat 99.9 percent of the people there, which far exceeds my achievements in any of those other activities. There's something enjoyable about that, even if it doesn't sound very noble.