I'm 40. I'm not sure if I have to try harder to learn. I was never bright in the first place.
I'm way more motivated to learn now. I only really watch Netflix etc on Friday and Saturday nights. Other evenings I try to get an hour to myself to do self learning. (Difficult with a child,!)
My main problem is I prefer learning programming related things not directly related to my programming job. Currently doing a course on network programming in c (I don't have a com sci degree).
What I really want is to learn maths to the point we're I can do a bit of calculus.
Just listened to John carmack on lex Fridman podcast. Very inspiring. He's switched in to AI research , never seems to stop teaching himself. (Though he has the advantage of being genius).