I chose a freelance career to have more of a personal life, so I make a conscious effort to ensure one doesn't hinder the other. I keep a calendar to stay aware of deadlines, I only work during certain hours of the day, and when it's time to chill, hang with family, or take care of myself, I make sure to do just that.
Occasionally, there will be some overlap. Sometimes things come up that require me to work a bit later or longer than normal. Or sometimes I just have more work because I want more money, but that is the exception rather than the norm. If it wasn't, then I might as well go back to working for someone else instead of for myself.