Decide before practice how you'll respond when frustration appears. Your goal isn't to eliminate frustration, but to stop it from controlling your performance.
During:
When frustration appears, take a deep breath, relax your body, take a short break, identify the problem, find a solution, and return your attention to the next thing you need to do well. Solve the problem rather than reacting emotionally to it.
After:
Did today's MindRep help you? How did today's MindRep help you? Do you want to own it and make it a consistent part of your training?