^Frustration leads to anger. When you are frustrated at another or at yourself, it quickly turns into anger, "Why do they do that? Why don't they do this? Why can't I do this? Why do I keep doing that?"
Let go of the anger when you are frustrated. Bypass the anger and go straight to acceptance. "It is what it is". It takes a little effort and it gets easier with practice. You gain an instant feeling of freedom.^