I make time.
See, to me, writing isn't a hobby, or something that I do in my free time, or something that is a burden. It's something that I genuinely love to do. I don't find time to do it, I make time. It became a priority in my life, and so I set up my life accordingly. Now, I'm not saying that everyone in the world has to do what I do, but this worked for me. If it works for you, great. If not, figure something else out.
First, I decided that I was going to take this whole "writing" thing seriously. I gave it a priority status in my life, and moved on from there. For me, my priorities are 1) my wife and kids, 2) my job, and 3) writing. Everything else that I do comes after that. Period. Karate, music, television, you name it, it takes a back seat. Ask anyone who is serious about their craft (no matter what it is) and I'm betting they'll tell you the same thing.
Step two: Once you decide that you're going to pursue your artistic endeavor, take a look at what you really do in a day. You can't ignore the wife and kids. For me, that's my whole reason for writing. Without them, I'd be pretty directionless, and I love them dearly. So whatever activities I'm doing with them come first. Then there's the job. Well, that pays the bills (mostly), so I can't really stop doing that, now can I? So now what? How much television do you watch? And how much time do you spend surfing the internet (reading blogs like this one)? How much of that time is wasted? Surely reading this blog isn't a waste of time, but c'mon, television? Biggest black hole time-waster of all time, and it doesn't really stimulate the imagination. Instead of watching the latest episode of "Big Brother" or "Dancing with the Stars," go sit down behind your keyboard and let your fingers do the dancing.
Third and final step: Set a goal. How much can you write in a day? How much before you feel you've earned a break? Setting a modest goal will help you sharpen not only your writing chops, but also your time management skills. There is no magic number of how many words to write. Everyone's is different. Stephen King advocates something like 10,000 words a day, I believe. I'm nowhere near that prolific (yet) and I do have other priorities, so mine is a more modest 1,000 words per day. Come hell or high water, that's what I do. End of story. Lots of folks write more than me, and lots write less. But do the math: If the standard length for a novel is between 80-90,000 words, how long will it take you at that rate to complete a first draft? Oooh...The possibilities are endless!
The point is, if you want to do this, you have to train your brain to work for you, not against you. Time? P-Shaw...You have all the time you need. You just have to make yourself use it wisely.