I just try to not let wins or losses ruin my day/weekend/week. I only play one league but it's a decent money league. I won the superbowl once two years ago and that was like getting a monkey off of my back. Now I can just enjoy the hobby and let the cards fall where they may. Once I actually recognized how badly it was affecting my moods I decided to "lighten up Francis..."
Also I don't play playoff leagues at all. Once the fantasy season is over I try to just enjoy regular football through the playoffs and superbowl.
This is similar to my situation. I used to take fantasy football way too seriously, and part of the reason I did was because I had never won a championship.
Beyond that, I was the #1 seed for three straight years from 2007-2009, and came away with only 1 playoff win and zero titles. In 2011, I recovered from a 1-4 start to go 10-1 the rest of the way and win my first title. Having that monkey off of my back I was able to step back and enjoy the game more. My emotional reaction, win or lose, is far less volatile than it used to be, because I think, "No matter what happens I've already won one. My name's on the trophy and nobody can take it off."
That said, this zen-like approach to fantasy football has coincided with a lot of winning for me. I went on to win back-to-back in 2012, and am now 10-1 and going for a three-peat. It will be interesting to see if I can maintain this c'est la vie, carefree attitude once my luck runs out and I start losing. I would like to think that I will. Winning a title really helped me to put things into perspective.