When you struggle with visual images which in-flame your passions, taking cold showers or running for ten kilometers may help, but that's not enough. There has to be more.
Go public with your commitment. Those of us who are uncertain of where we stand are much more prone to be swayed by emotion than by a knowledge of right or wrong. We begin to reason that God made us as sexual beings and put this furnace of passion with our bodies, and so surely to bring to fulfillment what he designed can't be wrong. Or can it?