Some of the most difficult lessons we must learn are not about endurance, sight-reading, or transposition. Those are relatively easy. More challenging are those unexpected humiliations inflicted by people and situations out of our control. They can stifle the very reason we want to do what we do. It could be criticism, energy-draining attitudes, or any unforeseen scenario that threatens our confidence. Learning to expect them and to deal positively with them is crucial.
Criticism can be our best teacher. When we bristle and get offended, there likely is some truth to it. We would do well not to react, but to improve. Use criticism as motivation for the next practice session. A hard to please teacher or conductor may be just what you need to make you a better player and person.
Prepare yourself for any negative attitude before it comes. It may be yours or your neighbor's. It's still dangerous because it is poisonous. Your passion for playing must be strong enough to withstand the disgruntled, the discouraged, and the critical. Counter with good playing, not anger. Let it develop in you strength and leadership. It is not your clever cutting reply, but the quality of your playing that will speak loudest and inspire others to follow.
Adverse playing conditions are arguably the hardest obstacle. Sounding great with no help means you are able to sound great with no help! A cello soloist I know used to practice in the winter with the window wide open. In the hot weather he closed all doors and windows and put on a heavy coat. No bad hall was going to get to him. Whether it's a gym or a closet, there you are, and you must sound great.
Ours is a coddled generation demanding the easy way with constant pats on the back. Politically correct thinking so prevalent today is that no one fails, and everyone wins. We insulate ourselves from hard reality, so that the truth smarts when it finally comes. Learn to take the hits so that your great music will thrive anywhere.