You are seeing this beautiful world through eyes. To preserves a healthy eye sight you have to do exercise for eye so that the muscles of eye gets strengthen and healthy.  Without moving your head you have to do this exercise while doing so you improves your eyesight, prevents eyestrain and the muscles of your eye gets strengthen. The fives exercises of your eye are

1.  Look up and then look down.

2.  Look at the right and then look at the left.

3.  Look at the top right and then look at the bottom left.

4.  Look at the top left and then look at the bottom right.

5.  Look up and then rotate your eyes clockwise and then anticlockwise.

You have to breathe normally while doing these exercises. Further you have to do it slowly to reap the full benefits.