I started exercising again mainly because it helps avoid or delay many of the conditions that come with age. At fifty, I can really hear that clock ticking. I

I started exercising again mainly because it helps avoid or delay many of the conditions that come with age. At fifty, I can really hear that clock ticking. It also doesn't hurt that being in better shape allows me to keep up with my daughter (now twelve) as we hike, ski, and engage in other active pursuits. Or that I sleep better. Or that I look better, though frankly that would never have been enough all by itself. Wasn't planning to be a model anyway. The key, for me, has been to tap into both my inner geek and my competitive nature. There was no way I could do this half way. As inanuthshellus put it, I had to make it part of my identity. I committed not just to running, but to being a runner. Starting out, I did a ton of research on techniques and equipment. I run more often than just about anyone I know. I obsess over form and metrics. I work hard to stay on leaderboards for various "segments" or "courses" that I run around town, each and every month (including winter). I'm loud about my running, to reaffirm my identify as a runner. At this point, quitting or slacking off would mean becoming less of something I have striven hard to become, so I keep going even on days when every other factor would point toward not bothering. This might not be the healthiest attitude in the long term, as my performance will inevitably start to decline some day and that will be hard, but so far it has worked for me. Fortunately, at least in running, there's still plenty of opportunity to compete within one's age group instead of being thrown in with all those twenty-somethings, so even if I do decline I can still hope to decline less than my rivals and my ego can remain intact.