Excellence can be obtained if you:...care more than others think is wise;...risk more than others think is safe;...dream more than others think is practical;...expect more than others think is possible.
Don't lower your expectations to meet your performance. Raise your level of performance to meet your expectations. Expect the best of yourself, and then do what is necessary to make it a reality.
You've done it before and you can do it now. See the positive possibilities. Redirect the substantial energy of your frustration and turn it into positive, effective, unstoppable determination.