There's no simple way to say this but it all comes down to one key thing and that is sacrifices. This question was put to me on a facebook post by a friend of mine Andy. He's recently had a baby and as you can imagine getting into his studio is hard. Plus when you've just had a baby you don't actually want to go in the studio, in your free time you want to spend it with your family, so I totally get that. Finding the time is hard especially if you work full time at a job that isn't involved with music. Let's say a 9 to 5 with an hour each way commute. You're home for 6, a bit food with the family, play with the kids. Next thing you know it's 8pm and knowing you've got to up at 6am you are looking to go to bed by 10. That leaves you two hours to get in the studio. But we all know it takes half hour to get in the groove.
I honestly don't know how to answer this question. The only thing I can say is sacrifices. You need to sacrifice something to make time for the studio. Do you play playstation or Xbox. If so that time can be better spent in the studio. Have an agreement with your other half that on a certain day you get to just do studio time after work. Cut the pub out. Go into the studio instead. On weekends wake up early don't have a lay in. All these things benefit your life in any way really, other than pass the time.
It all comes down to how much do you want to get into that studio. Because if you want to get in there that badly you will. You will make sure you are in that studio for as long as possible being as productive as possible.
Me personally I get a lot of studio time. I start at 9am finish at 5pm then drive home have dinner with my wife and kid, play around, do bath time and get my daughter ready for bed. Then as soon as she is asleep I'm working from home on my laptop writing articles such as this one or doing business related admin work till midnight. I'm fortunate enough to work in a studio full time so my studio time ties into my work time. But what I always aim to do is when I am at the studio I am working with things that can only be done at the studio. Anything that can be done when I get home is done when I get home on my laptop. Doing so maximises my productivity whilst at the studio and means that my studio time from 9 til 5 is constantly active. If you tallied up my work related hours you'd be looking at roughly 12 hours per day.