In reply to gingerdave13:
Some friends came to visit last weekend and we did a little hike up the end of the valley and we inevitably pointed out some of the trails I run on. Then the discussion turned to the ultras I'm doing this year, then obviously - why?
I'm sure its paraphrasing someone but "if you have to ask the question, you won't apprecicate the answer" is all I could think of.
None of the reasons I run are particularly logical or justifiable at a fundamental level. It costs money (travel to races, kit, food etc), it takes time away from my friends and family etc. However, its enjoyable (I only run outdoors, on mountain trails), keeps me fit, and I enjoy the challenge of occasional races.
To be honest, out of all of those, keeping fit bottom of the list - its a happy side-effect. I enjoy being outdoors, and running keeps me in the shape to do the things I enjoy.
Not particularly insightful I know, but I've found that since I got to running marathons and beyond, I got asked the 'why' question quite a lot. I've still not got an easy answer, but I've given up caring or trying to find one.