A little at a time.

Force yourself to do something every day, even if it's only 15 minutes of work. Write a blog post, research a technology, test some code, etc. Just do something to move your project forward. Progress is made in little steps.

As an aside, I've found that with kids, this is the way to get anything done. I just don't have large blocks of time I can spend working on stuff anymore. I've found that although it's inefficient to work in small increments of time, sometimes it's either make zero progress or make a tiny amount of progress.