One of the many gifts bestowed on those of us who have reached this age is an awareness of "what's happening", body-wise and other-wise. It's that little feedback "voice" and it's individual and highly truthful. Folks of all ages have the "voice", but at 50+, we learned long ago to listen to it. . didn't we all. ['Course, there are the "old fools" out there for whom there is no succor, but that can't be helped.]
You don't need us to tell you when to get out of the saddle for a spell. Feel like ridin'? Go have a ride. Feel lousy next day? Ease up. Simple. . .safe. . .effective. . .cheap.
A really wise "voice" will also advise you on other cycling related themes, like burnout.