Your eyes can serve you well for a life time, if you take good care of them and exercise them regularly.
If you don't use it, you lose it.
Eyes need to be used regularly in all the ways that you would like to be able to use them.
If you hardly ever read things close up, you will soon lose the ability to do so. If you don't take the time to gaze off into the distance you will lose that ability as well.
The good news is that if you have partially lost those abilities, with the right kind of exercises and practice, it can be regained.
Check out a book called, "Better Eyesight Without Glass" by a Dr. William H. Bates. Some libraries still carry it.
You can learn all about his book and system on the internet by going here: http://scifaith.visionheal.hop.clickbank.net/?exitoffer=0
The bottom line is that there are certain things that healthy eyes do differently from unhealthy eyes. You can train your eyes to do the right things to be healthy. Yes, it takes time. But of course you wouldn't expect to get into good shape without working out, right?
The keys are resting, blinking, shifting, sunning, and focusing.
Palming is the method used to rest and relax the eyes. Put your palms over your eyes and just relax until you see pitch black.
Blinking is important to cleans and clear and reset the eyes. Blink as fast as you can when every you think about it through out the day.
Shifting relies on the never staring at anyone thing, but constantly moving your attention from one area to another of the object you are looking at.
Sunning helps to accustom the eyes to light, so that you don't have to squint, or get eye aches when in bright light. Simply close your eyelids softly while outside on a sunny day. (Early morning is best, just after the sun comes up.) Orient your eyes towards the sun, but keeping the eyelids closed, slowly rotate your head back and forth as though you are trying to get a nice even tan on your eyelids.
Focusing is actually about the eye-mind connection. If you are looking at something, you should be thinking about it. If you are thinking about something that is not where you can see it, then close your eyes and let them relax while your mind does the wandering. In other words, don't just stare off into space while you are thinking about other things. It contributes to a disconnect between the eyes and the mind.
And of course eating healthy and living a healthy lifestyle will help everything to recover, recuperate, and regenerate, better and faster.