It is extremely variable. Your life is your work and your work is your life, to a degree. You make your own schedule, but there are realities to personal training to consider. Most people will want to train before or after standard 9-5 work hours, and you need to be available during those times. Your location tends to be your home base, and your life will revolve around it to an extent. I wouldn't say work life balance is amazing, but it's also not an issue if you love the job and the people. It is more "work-life integration", and you'll have to know if that's your thing before going into it.