If you have fun playing, people will have fun listening to you.
As a music student, you are constantly preparing for a lesson, an exam, a recital, an audition etc. There is always something coming up where you'll have to present something or compete with others.
This constant obligation to prove something to teachers, judges, classmates and yourself can become a burden if you're not careful about it. I personally went through a hard time in school until I told myself that if I wasn't gonna enjoy myself playing music, I'd rather do something else. My life changed when I decided to make fun the most important aspect of my playing. I became more relaxed and played a lot better. The results in exams and auditions followed. I also had much better relations with my classmates.
Take time to play pieces or etudes just for yourself with fun and pleasure as your only goal. No public to impress, no jury to win over, no conductor to follow, no teacher to satisfy, nothing to prove and nothing to explain! Chose pieces you won't be performing for anybody. Just music you really like. It can be something new or something you played before. Just enjoy yourself. When you go back to the pieces you need to prepare, you'll feel much better.
Make the fun aspect of your playing just as important as rhythm, intonation, tone and musicality. Those aspects will improve if you enjoy yourself, trust me.
I am associate principal horn of the Singapore Symphony Orchestra and the author of the progressive methods. I'm happy to share my experience as a horn player and teacher with you.