I work still and will continue to work till at least 67.
I'm a developer and development manager so I get to challenge my brain routinely at work. I consume nuts, lots of and a variety of tea, a little chocolate and some red wine to help with polyphenols [1]. Oh and Omega 3 fatty acid sources. I am actively getting my weight under control.
I play puzzles, board games and other things to stimulate my brain.
[1] https://www.researchgate.net/publication/308945733_Nutrition...