Works in cycles
Sometimes it seems to work in cycles; you feel strong for a while and then start to lose the strength to guard your eyes, and sometimes it can take time until you get that strength back. But remember, every time you pass a test, every time you overcome the downward part of the cycle, G-d puts away a diamond in his treasure chest for you. And he might even give you a little break for a while where you are feeling strong. But G-d doesn't want you to just have one diamond. After all, if we passed one test and were done, we may as well die. But G-d gives us 120 years on this world because we can accomplish so much with each cycle, with each up and down... So after a while, he makes us lose everything and start over from the beginning again, so we can keep getting diamonds. He suddenly makes us feel as if we have never worked on ourselves before and we need to find new strength each time to overcome the downward spin. This is G-d's way, so we keep working and earning, putting away bit by bit and ultimately doing great things for ourselves, for G-d and for the entire universe!