If you have a good idea, write it down. Writing out your thoughts everyday can expand your brain power to great lengths. Keep a notepad at home, car, backpack, a small one in your pocket, get a notepad app, WHATEVER! WHEREVER!
Another way to exercise your brain, DO MATH! If you do nothing that pertains to any math problem solving, download the MATH WORKOUT or THE BRAINWARS app and hopscotch through math challenges. You scroll through your Facebook anyway so give your brain some pressure so it can be stronger in the long run.