A good friend and I had this discussion a few days ago. Both of us are in our 50s and are pretty active. Bith us agreed we feel much younger than we are physically. Neither of us feel wore out or overly tired. We both try to work outrl regularly and eat right etc. I think my job helps me in that regard too. I have times where I have to buckle down and get back on track but I rarely if ever feel like I am 54. I am in pretty good health all in all. Only medication I take is a thyroid medication.
I get told fairly regularly that I don't look my age either. Usually when I have to show ID. My wife will tell you I damn sure don't act 54.....more like 14.....
I think that is a big key too. Staying young at heart and mind too. I never ever want to be the grumpy old guy.