Juggling makes your brain bigger
Skip the Chessmaster JB. There is another study on juggling that shows both an increase in the amount and density of grey matter after six weeks of juggling 20 minutes a day.
I think concentration is the key. Now that I have given up better living through chemicals, I am happiest when I am absorbed in something. My yoga/meditation practice is fitting the bill, but I seem to be on a plateau right now, so perhaps I need to change some things.