I sat down and came up with "replacement thoughts"...things I want in my R that make me feel better, and when I start thinking about my H with OW, I stop the bad thought and replace it with one of my choosing. Sometimes I have to do it out loud. Often, I have to repeat the new thought over and over. More often than not, I am able to get my mind off the bad stuff and into a better place.
Some days take a lot more effort than others. But I'm winning the battle.