If shmiras ainayim seems so hard, take minute and think about how often you are really tested each day. Most people will find that they have tests in shmiras ainayim only a few times a day, for short periods of time. If you look at it in the context of 24 hours, it's really not that much of the day that we are being tested. That alone should gird us with strength for the times we need it.
Also, one of the best strategies in fighting the Yetzer Hara is not to be caught off guard. If you know in advance that these few times a day are the biggest tests, it's much easier to deal with it than if you're hit with the tests without being ready. Always anticipate the tests in advance, and be ready for them. And before you enter the "test zone", encourage yourself, say a prayer and think of your goals in life. With this strategy, you will find that 90% of your daily tests become much easier to deal with.
This is also another strong reason to get a fool-proof Internet filter, if you don't have one yet. Someone who doesn't have a good filter is tested in shmiras ainayim many hours of the day, instead of the usual few minutes here and there that most of us are tested with each day. So if you don't have one yet, get one today!