Never underestimate the value of each and every time you say no to yourself. Sometimes a person is feeling weak and says to themselves, "what's the difference if I look now at something that I know I shouldn't - I'm anyway not feeling strong now". You must believe in the significance of saying no, every time, no matter for how long and no matter for what desire, be it a big sin or even a quick gaze at a woman. Tell yourself, "Now I will not look, now I will turn away. Later I may look, later I may fall, but just for NOW I will be strong". You must believe in the significance and importance of every time on it's own.
This is a powerful and proven way of making significant progress in the long term.