It seems there are a lot of services out there that purport to provide some benefit, but I'm hoping some folks in this community can point to something true, even if it isn't necessarily fashionable.
Remember that a good diet is also important... https://www.organicfacts.net/most-unhealthy-foods.html
For general health, weight training is more important than cardio, but for mental health, stress resilience, and cognition, cardio is our more powerful tool.
Read about mental models, read about meaningness, and learn to view the world as a fractal system of systems. I find that reading about ecology, psychology, and sociology to be particularly helpful in building/debugging my mental models, especially my models of other people’s models.
That said, getting enough sleep and exercise wouldn’t hurt.
I was just reading a book called "The Secret Life of the Grown-up Brain: The Surprising Talents of the Middle-Aged Mind." One chapter discusses the 21st-century discovery of the brain's ability to create new brain cells in a crucial area....after exercise. It ran counter to 100 years of biological theory, but it was confirmed and confirmed again.
Exercise.
The only thing I'd add is: lowering stress. (Because stress damages your brain.) Meditation, sleeping well, having a healthy social life can all help. Basically, if you start taking basic steps to improve your general health...you will in fact improve.
Motorcycling (Keanu Reaves), martial arts (Joe Rogan), surfing (Anthony Keidis).
If you put your body at risk, your mind has no choice but to stay quick. Be careful though!