you can use 'life's too short' when saying that you don't want to get angry, worried, or overworked because it's a waste of time - you would rather focus on something good than waste time on something bad
I'm not going to get mad at Karen for being late. Life's too short! Let's get this party started!
Life's too short to worry all weekend about my test score. I'll find out on Monday, but until then I'm not going to think about it.