Respect for your age
I have been pushing some pretty intense workouts the in recent weeks, training hard with weights, and I notice how when I really work my muscles hard, it now takes me at least 3 days to stop aching and fully recover. I don’t mind pain, I could train after 1 day or 2 no problem, but I will get progressively weaker. In order to train and get progressively stronger, I now need 3 days between really heavy, intense workouts.
It's an age thing!