I am 62, and I have been riding bikes since second grade, but I really fell in love with biking delivering morning newspapers.
Daily commuter bike: Trek 7700
Mountain/trail bike: Trek 8700
Winter beater: Trek 4500 with studded tires
Daily supplements: multi-vitamin, glucosamine+condritin
It's not so much that I have slowed (I can still outbike the best Boy Scouts in our troop on a 25+ mile tour or on a flat out race), as that it takes me longer to get back into shape after the winter layoff here in Wisconsin. I've never been a racer, though. My solution: studded tires for the winter commute.
In addition to daily commuting, I take overnight and all-day bike tours with the Boy Scouts in my troop and with family members. I'm planning a long tour, perhaps the Pacific Coast before biking coast to coast, but I'll do that on a recumbent.
Keeping track on my annual mileage has not been important to me, but I'd guesstimate it at 2,000 - 3,000 easily.
For a number of years I ran every day at lunchtime, but it was so boring I switched to biking back and forth to work, which I find much more fun and interesting.