My foray into Category Theory so far has been reading "The Joy of Abstraction", which is a layman's book to CT. So far what's she's written makes perfect sense and would be mostly obvious to anyone who hangs out on HN. Moving up and down various levels of abstraction, the idea of "functions", as I read this I'm basically thinking it's what I've been doing for the past 40 years, not a big deal. We'll see as I continue in it.
Circling back to the original question, it's hard to assess my learning ability since I'm not venturing out into totally new territory for me.
When you have a job it's hard to fit in as much exercise etc. as you want, it's easier when you're retired. But also when you're retired it's easy to fill the time with other things, errands, as you get older medical appointments, and motivation is a little harder since you don't have deadlines on your projects. Work comes in spurts interlaced with reading, which is important but doesn't move the projects forward.
I do exercise regularly, especially after the heart attack. "Make these changes or you'll die" makes a great motivator.