I have long tried to emphasize this in "tactical" discussion threads. Your body is part of the equation, and All Hell Breaks Loose situations aren't going to be easy or unstressful. Better to be in the best shape you can for many reasons.
I am perpetually swamped at work, so it takes real drive to work out, but I still manage to do it, at least a couple times a week and home and in the gym on the weekend days. You truly DO think differently about yourself and the world around you when you feel and look great.
And regarding age....Chuck Norris is 71 and still in pretty darn good shape. He's my role model for old age.
Mauser Werke, Schmidt-Rubin, Remington, Colt, H&K, Weatherby, Browning, Ruger, Marlin, Mossberg, Saiga, S&W, Sig Sauer....a few friends of mine