None of those things will necessarily stop you from wearing glasses. For most people wearing glasses is genetic, if one of your parents wears glasses you might also. Your eyes are genetically programmed to start and stop changing at a certain age. You can't stop them, you can however prevent them from changing more then they are programmed to go by not straining them, like if the doctor tells you to wear you glasses all the time don't try to see in the distance without them, it just strains your eyes. The other thing you mentioned strain your eyes too, but not doing them will not improve your vision. The other thing that can make you wear glasses is poor nutrition. Even if you were never supposed to wear glasses not getting all the vitamins and minerals developing eyes need might make your sight drop, so make sure you eat your fruits and vegetables and everything else you know you're supposed to.