I am reminded of Nassim Talebs interesting ideas on making sure you stay exposed to some stressors in your life, if you're still with it. By that I don't think he means challenge the local moto-taxi rider to a fist fight 🙂 but to do things that put you outside your comfort zone. I watch my 83 yr old mother suffer a slow slide into nothingness, doing the one thing she still enjoys and the rest of her day and week is in front of the TV and I contrast that with others of a similar age who are nothing like this. One 80 yr old I know is entering a power lifting competition for example.
More travel perhaps, dealing with immigration can be a stressor 🙂 haha with some "flanuering" type travel mixed in, i.e wandering places with no fixed agenda and seeking joy from the unexpected you may encounter. A rail trip from Veintaine to Laung Prabag on the high speed rail, walk around the old city, along the Mekong mini bus out to the Kuang Si (sp?) Waterfalls and go for a swim etc, then fly back home
Volunteering to help others less fortunate seems rewarding to many as perhaps another option, my parters mother is 78 and does that 3 days a week and seems engaged.
That said, I am 59, I as yet don't have the wisdom of age. I am observing the 75-80 yr olds I know though for that exact reason though. I am also cognisant that those who are easily bored make for <deleted>ty company. I retired when I was 35, there always seems too much to do and not enough time. Perhaps this will change IF i get towards 80 ?
NB "Anti-fragile" is a good read, I'm on "Fooled by Randomeness" right now
https://en.wikipedia.org/wiki/Antifragile_(book)