Asking for feedback from your instructors is another way to measure progress. So many times I have given in to my mediocrity. In doing so, I sometimes gave up on my dreams. I work out because it is the right thing to do. Perfect practice does not make perfect.
Practice makes improvements, and improvements lead towards excellence.
Excellence is a progressive process. It isn't obtained in an instant, but takes time and consistency. However, excellence is permanent when you finally attain it. Good enough, isn't.