Ever since I can remember, I always wanted to run a marathon. I had run a couple half-marathons. I either needed to go faster or farther--farther is MUCH easier. At the age of 36, I got the brilliant idea of running "four before forty." I completed my fourth marathon last fall--at the age of 39 (and a half). I really struggled to fit the four weekly workouts in--I've very slow (if I ever break 10 minute pace on any distance, I'm thrilled).
which still isn't saying much), but I'm happy with how I feel.
Running a marathon skews your perseption of running distances. You forget how walking a 5K can be a very admirable goal. You forget how exciting it was when you ran five miles for the first time; that distance is a "short" run during marathon training. You forget the pride you feel running your first "double-digit" run. I never was a super exercisor--I only ran four days a week (I am a self-proclaimed "under-achiever exerciser").