Does anyone else have a husband with an out-of-control running or exercise habit?

I need some advice. I have been married for 15 yrs. and have 3 children. During my first pregnancy, my husband began running. Just prior to the delivery of our first child, he ran his first marathon. After that, he was hooked. As the years ped, our family increased by 2 more children, and his running habits also increased. At this point he has run countless marathons, 2 50-mile races, and is set to run a 100-mile ultra marathon in October. He runs every day, including holidays (yes, Christmas included) and steps up his running during vacations (family or otherwise). I feel that running has taken over his life to the point where all his other interests no longer matter (he used to surf, skateboard, play football, dirt bike, etc.) Worst of all, I feel I come in second to this running addiction. (He claims he's not addicted, whatever). I have become resentful of the time/energy he puts into running and we have had many fights over the years about him cutting back. He has tried to get me interested in running, but I hate it and would never be able to keep up w/him anyway. He has told me to find a hobby of my own, if I did find a hobby I took to that degree, we would for all purposes be leading separate lives. Our marriage is good in all other areas, but I don't know if I can spend the rest of my life as a neglected cheerleader to his great pion. I want him to be as enthusiastic about spending time with me as he is about running. What can I do?