[abbietmp]

Oh I think that you need to try puzzles for sure

If you've never seen Simon Tatham's Portable Puzzle Collection, I can definitely recommend.

[Greenleaf]

Recap the things you have done for the day, it improves our memory as well as keeps our brain active. Don't let yourself to be idle. Engage yourself in activities which you like to do.

[Miamoo]

As most members have suggested the only way I suppose to keep your brain active is to attempt something or some job which you have found challenging. Even a simple crossword puzzle or anything which challenges your mind without getting you frustrated is good enough to make your brain ask for more. In short engage in anything you love to do. Simple as that.

[SaltyRG]

focus on one thing and do it proparly

[Mishapr]

They say that reading books improves your speaking style, solving crossword puzzles makes your vocabulary richer, and solving quizzes increases productivity and allows you to do any task. At least this way I train my memory, knowledge, and learn something new, for example when I come across a question, the answer to which I do not know, then I turn for help to quiz solver website that he helped me solve the problem.

[FataL]

Give chess a try, or a technical martial art like BJJ, theres so much theory that your brain will be whirring day in and day out

[benjamin82]

Always challenge it. Try solving hard problems. Keep track of what it thinks about everyday. I have an intellectual journal that is 10 years old archiving all my thought experiments