Teaching too many Yoga Classes

My first blog entry has been inspired by my recent yoga teaching experience. As a full-time Graduate student I need to find balance between my practice, my teaching and my school work. Yesterday, I hit a wall.
I enjoy maintaining a physical lifestyle, however, it is important to maintain your energy levels. When proper bed time arrives this is when one should be drowsy and exhausted. Yesterday, I was drowsy and spent by 10:00 a.m. after my 80 minute bike ride. My yoga instruction suffered at 4:00 p.m. and I managed to complete no schoolwork. It was a day of rest.
I am now in search of finding balance. I want to keep teaching everywhere but I cannot be teaching semi-quality classes. My passion for teaching is rooted by my energetic approach to each class I instruct. My regular students are aware of this and sensed my awkward approach to class yesterday. I have two plans of action. I plan to limit the number of classes I teach per week. I plan to limit the amount of demonstration or practice I display while teaching. Life is full of learning from your different paths. Soon I know balance will present itself. How many classes should one instructor teach per week? How many classes should one instructor take?