Exercise your brain

Read every day for at least thirty minutes.

Write.
Express yourself creatively by writing a narrative, poem, love letter, journal entry, or anything else that comes to mind.

Learn a new language.
Start learning any new language you prefer.

Play in a digital brain-training game.
Choose some brain game apps and play them every day. One example is the BrainHQ app.

Practice some art.
Create works of art in whatever form you like: paint, draw, sculpt, shoot pictures, knit, weave, etc.

Become a volunteer for a cause you support.

Complete a crossword puzzle, jigsaw puzzle, or sudoku daily.

Go to work in a different direction.
Take new routes whenever you can and wherever you go.

Simply try something new.
Do something out of the ordinary every day, whether it's learning a new skill like cooking or golfing or just watching a video about an unfamiliar topic.