A person who just found out that he has a serious disease, or someone who is ill, in pain, or just lost a large sum of money - it's unlikely that such a person would be having a difficult struggle with shmiras ainayim or improper thoughts at that time. Suddenly these type of desires would have no meaning, they become irrelevant in light of "more important matters" at hand. It's only when one is healthy, financially stable and feels comfortable with himself that he can start to forget his priorities in life and begin to stray after self-gratification.
If we keep this in mind, it may help us in the struggle. Let's appreciate what we have now and pray to G-d that we should never need to come to tragedies -G-d forbid- before we "forget" about how "difficult" our struggles are in these areas.