I saw a man in his seventies running and jumping and doing sit-ups and push-ups and I said to him,"Why do you look so sad and depressed, you can run miles, and do hundreds of sit-ups and push-ups you're probably in the best shape of your life!!!" He just looked at me with those sad old eyes and said "yea but there is something I can't do, I can never be eighteen again" He just turned and ran off!!
All the best