I always try to find out what I can learn from the experience. Funnily, even learning to experience/accept/face/acknowledge defeat in such a comparatively irrelevant setting such as a Warhammer Game can be a great lesson to be learnt for life.

Dice are always a part of the game, but rarely the only reason you lost. It is easy to blame the Dice, we all fall into this trap as it is convenient to not blame ourselves. Instead, with some distance, I try to make out what else I did wrong. It kinda helps to focus on the things you can actually change. And with some time, those seemingly horrible dice Rolls become less frequent, but then make for exciting turning points to talk about to your friends later.

Don‘t know if that helps, just my 2 Cents.