When you have an unwanted emotion, trying to make it go away will only prolong it. trying to ignore (flee from) it, will only make it come back faster.
But when you allow it to be, and be fully present with it, It will exhaust itself and go away.
Surf the feeling.
A feeling is like a wave. It starts small, Then it grows towards a climax. After which it ebbs away.
Ride out the wave.
Why is this metaphor useful?
I often feel resistent to being with unpleasant emotions. This metaphor helps me, because surfing sounds more fun! It removes some of the friction towards experiencing the emotion.