To people who are building a side venture and also have a 9-5 job - how do you manage your time?

I get up very early (between 4 or 5am) and start working on my side venture. I don't eat breakfast (not because I'm a mad hustler, but because I've been doing intermittent fasting for a while anyway, and found that skipping breakfast actually is good for me). This gives me a solid 3-4 hours per weekday, which I think is actually more than enough. My biggest challenge is not so much finding the time, but making sure that I consistently stay focused on high-impact activities. I very easily get sidetracked from main priorities, and descend into what I think of as busywork: Doing things that contribute to my venture, but really are not "this is moving the needle significantly" stuff. I'm still in the process of figuring out what works for me in this regard.