I'm 50 this year and I've never been fitter and stronger since I took up running 5 years ago.
This has had a powerful effect on all areas of my life, so I can truthfully say I've never been happier, either.
However, a word of caution.....ageing is inevitable and I now find that I cannot get away with being unkind to my body like I did from my teens to my thirties - I mean xs alcohol, junk food, all-night partying, workaholism etc. In fact, to meet the running challenges I set for myself (and stay in the same waist-size jeans) I have to lead a very balanced, and some might say boring, life.
I don't think it's boring - I'm doing my first fell race on Easter Saturday! Me! A middle-aged lady! A lorry drver half my age leaned out of his cab and wolf-whistled as I ran past yesterday - then looked gobsmacked when he saw my smiling, wrinkly face!
PS - an upper body weights program twice per week keeps the arms from developing those underarm flabby "bingo wings".