Build my own business while working as a leader for a fast paced company.

Somehow I think I have a belief system as if I can either do one thing or the other but not both at the same time. Is that wrong? When I start thinking about the possibility of having my own business and what that will do for me and my family it starts off very exciting and very motivating. However, when it comes to writing down all the actions that will be required for me to do that, my brain wants to go in “I don’t know”, confusion, doubt and fear. In turn, I get very overwhelmed and don’t take any action at all.
On one hand, I want to be the best employee I can be at my current job, I love to work but on the other hand, I also want to take action towards building my own business.
One of the things that concerns me is burning myself out, not being available for my daughter, sleeping in front of the computer while I am in bed attempting to work towards that goal (has happened so many times). I wake up every morning at 5am to read for 30min and workout for another 30min. I have a long commute Mon-Friday to my current job, which is about 40min each way so I leave my house pretty early to drop my daughter off and head to work. I am off on the weekends. I am back home at 6pm every night. I serve dinner by 6.30pm, give my daughter a bath and go to bed by 9pm.
What kind of thought work should I do in order to believe I can build a successful business while still giving my best at my current job? I don’t want to be at my current job forever but do want that income to help me one way or another to invest it in my own business. When I think of my available time to put towards my own business, it seems so little it disappoints me if that makes sense. Do you have any recommendations to do a lot in short amounts of time? I want to work smart more than I want to work hard and get nowhere..