How to keep your brain young?

Image by OpenClipart-Vectors from Pixabay

Frank Burnet has a degree in Biochemistry from the University of St Andrews and a doctorate in Neuroendocrinology. He is the first professor of Science Communication in the UK and a founding member of the Cheltenham Festival.
I talked to him years ago on how we can train our brain so we can use it better and keep our mind sharp.
 
"The brain is like your leg muscles. Basically if you use it, it gets better and better. So actually the brain is much more flexible than we once believed and you can train it. Particularly if you're older like I am, basically you can really improve the way your brain is working. For example you know doing simple uh mental arithmetic - by doing puzzles, by doing crosswords, by talking a lot, actually by generally thinking, and arguing, and discussing, and being active. The thing you must do is keep your brain working".