Great performances follow great rehearsals. Great rehearsals require great practicing. And great practicing is characterized by clear thinking. Needed: daily generous doses of sanity.
Helpful adjectives for your practice sessions: calm, patient, organized, purposeful, controlled. Not: frantic, hurried, haphazard, out-of-control.
Inspired energetic playing must first be disciplined. Inspiration without discipline is as useless as discipline without inspiration. You must develop both, but discipline comes first. At the end of your day, you want to be satisfied that you worked efficiently, not frustrated that nothing happened. The improvement you want won't happen with fruitless frantic flailing.
Sloppy practice never produced a polished performance, but it does give your nerve demons permission to wreak havoc on your performance! Preparing to do your best is better than hoping for the best, which is insanity.