Wear red: In a study published in Emotion, researchers found that participants who were shown the color red had quicker and more energized reactions for a short period. Try wearing a red warm-up or leo in your afternoon class.
Compliment a classmate: In a study detailed in Harvard Business Review, researchers found that people who paused what they were doing to give someone a compliment felt an instant boost in energy and mood.
Learn something: The same study found that people who used a break from work to learn something new felt both their mental and physical energy increase. It was especially successful when they learned something related to their work. Try studying some videos of a variation you're learning and working on your interpretation. You may feel more energized and ready to tackle your next rehearsal.