Here's what helped me after a 15 year addiction. . . A rabbi was saying that if you would rather DIE than eat a bug, that Hashem won't have it happen that you will ever eat a bug. I had heard this before as a Chasidic story, but the Rabbi said it in such a way, he said that if there is any sin which you would rather DIE than do it, than Hashem won't let it happen that you will sin. That teaching hit me like a ton of bricks. That was about 5 years ago, and I haven't committed an act of s hefichat zera levatala since. I basically picture myself dying a gruesome, horrible, torturous death every time an urge hits. This took a few minutes sometimes, which was the time it took for me to come back to my senses. In the beginning, I would say I had to do this sometimes 15-20 times a day for the first year or two. Nowadays, I only have to do this a couple of times a week. I always need to come up with new, gruesome, horrible ways to be tortured and die, new ways that strike a chill up my spine and snap me out of the grasp of the other side. Some might say I'm a sick for having such gothic thoughts, but I would truly rather die than go back to that avierah, and this visualization really really helps. Also, after each Visualization I SMILE and say THANK YOU HASHEM!