I once read in an article about running that it makes little sense to answer when someone asks you why you run an ultra, because they won't understand anyhow - if they would get it they wouldn't ask in the first place.
There are two implicit suggestions here, that as a non-runner you are kind of opaque, and that as a runner you are clear about your motivation. Not sure I agree with either. I am not into many things and I don't do plenty others (gardening, whoring, cake baking, scuba-diving, playing the flute) but I get it, why some people do it. On the other hand, I am not sure why I want to run a hundred miles.
Sure, I can give a list of reasons, all of them more or less in the target area, none of them hitting the exact mark - I long to do something bold, it's cool to engage my body, I want to conquer new territory, I want to be proud of myself, life is waiting and the start line, I need a new belt buckle, I want to see how far I can go. I can even paraphrase an old song, improvise on poetic meaning, "'Lord, I'm 100 miles away from home' so I thought I might just run home."
But I still don't know - why would I run a hundred miles? Why would I do that to myself?Why submit to all that rigor, why give up so much time, why go through all the pain and fatigue?
More than once after a big run, 20 miles give or take, hours and hours of pounding the ground, feeling I had more than enough, I ask myself: 24 hours of this?
24 hours in principle, that is. Might be more like 30 in fact.
Then the next week comes, and I do it again.