Open your eyes wide and look at the 12 o'clock position for a while, then look down at the 6 o'clock position for the similar amount of time. This is basic eye exercise that helps restoring eyes balance.
Rub palms of your both hands and then rub them on your eyes wide open. Leave both hands after rubbing gently on both eyes. This will also help restore balance of your eyes. The heat generated through rubbing the palms leaves the eyes relaxed for a while.
Repeat these exercises for 10 minutes, then do the same exercise horizontally by looking first at 3 o'clock position and then 9 o'clock position. Do not spend more than 10 minutes on these exercises. Also do not press your eyes too hard.
Working with Marsden ball also helps improve your longer vision, and can also give some good sports skills.
Work out your ciliary muscle on a regular basis. This will help you improve your vision.
You should also spare some time to give your eyes some relaxation if you are working with closer objects. For example, people who work on computer for long shifts are recommended to give their eyes some time off after every hour.
Get your eyes inspected on a regular basis. It is possible that you have been suffering some problem, especially if you work closer objects and do not know. Having your eyes examined on a regular basis can help you prevent any major lapse in eyesight and your eyes stay healthy in the longer run.
You should also use sunglasses if you are out in the sun heat. In excessive temperatures your eyes are prone to be as much affected as any other part of the body. So you should take care of them.