An agreement and promise we made to each other before we got married. It's not a magic spell. Wasn't always the easiest thing to do but it was near impossible to not remember. The memory hitting one or both of us at bedtime and with it a softer more reflective heart.
The process of trying to stop arguing before bed, of trying to keep the promise almost always caused giggles and fits of laughter trying to keep strait faces when thoughts of promises made years b4 when we were wild and free and not parents of five. It helped tremendously for the entire 16 years of our marriage. We went separate ways over 20 years ago now yet have remained friends since. Probably helps there too.
My current spouse and i will celebrate our 14th anniversary this August. We have not gone to bed mad at each other either. Yet. :D