I am 42, and am only getting better with age and wisdom.
Running is about third or fourth on my priority list, but that's pretty high. I'm a busy guy. My family comes first. I've got a few great runners in the bunch - watch out for them!
Did 12 miles on treadmill, with each mile a little faster than the previous, eventually building up to and through marathon pace. Felt quite solid. Did one round of Ozone cross training ("endurance") before had to run to drive carpool.