If you are under the illusion that you can start a business and run it at your life's schedule, you are mistaken. The business is like a starving puppy - when it needs to eat, then it needs to eat regardless of what you have going on personally.
My hobbies include maintaining my physical and mental health. It's a full-time job. Yoga definitely helps for both of them. I'm a big fan of relaxing and not having a schedule. That's my best way to keep from going crazy.