Most nisyonos require (as the ba'al haTanya and many others say) a bit of suspension of our Da'as. We seem to lose our brains at the point of nisayon - and are left to proceed on what feels like blind heart, alone. I cannot count the times I went without the lust temptation for what felt like no rational reason whatsoever! When I have a lust temptation - at the actual moment of true choice - it boils down to me feeling that I really need this crap. It truly seems to be in my best interest and there is no logical answer I seem to be able to grasp onto. The mussar is all slippery in my hands. But when I "overcome", it is usually by me just figuring that there were so many thousands of times that I went with the lust 'just because', and that it was now my turn to suspend my judgment of what's better for me and go without it - just because. In other words, sometimes, all the hundreds of meetings, thousands of hours of step-work, and thousands of shares in meetings I have made, all boil down to a moment of letting go of my judgment and accepting Hashem's judgment instead of mine. And doing without what feels like it'd be soooo nice.