I'm reading Water for Elephants by Sara Gruen right now. In one of the beginning chapters, the main character discusses how when you're a child you can pinpoint your age to the exact month, when you're in your 20's your age springs to mind rapidly when asked, but when you hit your 30's sometimes you think of yourself as a year or two younger than you actually are. Denial? Maybe. Or maybe it's just the beginning stages of your mental fitness starting to slip.

Exercising your mind is just as important as your physical fitness. If you want to check your mental prowess, try out this fun brainteaser quiz on Good Housekeeping. The test is adapted from a Mensa quiz and it's not easy. But it's a good workout for your mind.