Editor's note: Keri Gans is a registered dietitian/nutritionist, media personality, author of "The Small Change Diet" and spokeswoman for Aetna's "What's Your Healthy?" campaign. (CNN) -- Your mom probably never gave you better advice than when she said, "Eat your fruits and veggies." But eating healthy may seem harder come fall, when favorite produce options dwindle and less familiar ones appear. Never fear. Now that warm months are gone -- and with them ...