You go to the gym three times a week to build muscle tone. You run grueling intervals to boost lactate threshold. You even skip dessert in order to stay in top shape. Nice work. But before you pat yourself on the back, answer this: Are you ignoring your most important athletic asset? Every move you make, from bombing singletrack to shooting hoops, starts with vision. What's more, your eyes can be trained to perform better. To be precise, it's your visual skills, not vision itself, that improve. Only glasses, contacts, or surgery can correct poor eyesight. But follow our advice on eye care and exercise and you will, quite literally, see the difference.