Can someone older keep their youthful vitality?

Well let's see. I'm 68 and I just got in from digging a drainage ditch in my yard by hand (can't get equipment in), laying down under layment for a french drain. Prepared a three course meal and am now sitting here typing. BTW - I only quit because I ran out of daylight and material. I'll be going to get more material and finishing up the job tomorrow. That will make day three.