I'm a youngster here, I turned 50 in Jan this year.
I hadn't ridden a bike at all in the last 10 years but decided this year was as good of a time to start up again as any. I started slowly in late April (Michigan seems to have two kinds of weather, cold and hot) doing 10 to 15 miles a day the first week then adding more and more miles as the weeks went by. I'm now up to 50+ miles on my weekly long rides (Saturdays and Sundays).
Had you asked me back in April if I thought I'd be riding 50+ miles a couple times a week by this time of the year, I would have answered with a solid No. I think the combination of starting out slowly and gradually building up the miles on a regular basis and reading all of the encouraging reports posted here has given me the confidence and courage I needed to keep going.
My goals at the beginning of the year were to get into shape and lose a few pounds. I've modified them slightly with the addition of doing a Metric later this month and, perhaps a century this fall.