I don't care if you're a personal trainer, a college strength coach, or some kind of bodywork magician; it seems like e-v-e-r-y-one in the performance/fitness industry let's themselves be absolutely abused by either their bosses or, even more common, opts to do it to themselves.
As a young personal trainer, I worked for a mega corp style commercial gym. On the outside they appeared pristine, seeming to represent the utmost in family oriented values for their members and employees. But behind the scenes, the personal trainers (and other staff) were pressured to work split-shifts under a heavily sales-driven structure. We were essentially told to be available 24 hours a day. Please tell me why a personal training session should be available at 2am? Generally, my days would start at 6 or 7a and finally sputter to a halt around 8p. Gross. So what if I had a few hours "off" in the middle of the day? When was I supposed to have a personal life?
Fortunately, as a college strength coach, things got better - much better! Thank goodness. But, the hours could still be intense and required constant management to ensure it didn't creep out of control. Why should you be expected to be at work by 5:30a and go all the way until 8p for a $35,000/year salary? The answer: you shouldn't.
My point is this: when you are really passionate about what you do for a living it can be easy to work yourself to burnout. It is a thrill to help others in the way that is supported by this burning passion. But there is nothing, and I mean nothing, wrong with adhering to reasonable working hours. Just because you love what you do, doesn't mean you forever have to punish yourself for it by driving yourself into the ground on the same old hamster-wheel.
Aren't you ever just a teensy bit jealous of the clients you see after their work day ends when you know they probably woke up later than you and definitely started their work day after yours. And yet, somehow, there they are enjoying their personal time with YOU who is still working! Get that sh*t under control!
Treat your passion like the business that it is. Businesses deserve respect and with that comes the ability to set a reasonable schedule and stick with it! Stop bending to your clients' or teams' every scheduling whim. They need to work with you, so set your schedule and let them fill in. Online schedule systems are a very affordable, easy, and incredibly awesome way to accomplish this, by the way. Check out ZenPlanner and MindBody for starters.