Okay, this suggestion is not an easy one...or at least it never is for me when I do it. Actually, these are multiple suggestions...all which I do/have done myself to get my proverbial ass in gear.
1. Read, read, read. I have found a direct correlation in the amount of material and how often I read and the productivity, frequency, and ease of my writing sessions. I usually read in my genre, but that's just me. Just the reading primes my mind for creation.
2. Just write. Anything. I think somebody said before to write a short story. I've done that and it helped a lot. Simply because I finished something. A little sense of accomlishment can be a very encouraging thing when you're in the long haul of writing a novel.
3. Stop stressing over it. The more I stress about the time I'm not writing, the more difficult it is for me to concentrate on writing...it becomes a vicious cycle for me because I can't write when I'm stressed out. This is the trickiest problem for me to get around, and sometimes if there's a busy time at one of my jobs or some other outside factor, I can be off my game for months.
4. Always remember that the more time you spend away from the story, the farther away you will grow from it. Try to write something about the story every day. It can be anything, even merely rereading the stuff you've already written. Anything to keep your head in the story. You will feel the distance growing the longer you are away from the story, and that goes back to stressing about lack of writing.
5. Finally, sit down and figure out the circumstances that you need to be able to write. For instance, instead of trying to force my writing time into the rest of my life whenever I could fit it, I analyzed my life and my routine, etc... and finally figured out the optimal situation. Personally, I need a very large block of time set aside, at least 4 hours. I've had to move this 4 hours before I go in to work, because I'm brain dead after I get off work. So this means I have to wake up at 4am every morning...which in turn means I have to go to sleep at 10pm. I'm still getting used to this schedule, but when I get it working I think I will be happy as a clam. I just adjusted little things in the other areas of my life so I can create the right circumstances for me to write. Does that make sense?
So there're my helpful (hopefully) insights into the cure of the infamous writer's block. Again, I realize all of these things are very hard to do, and very easy to write on a blog. I've done them all, and will no doubt do them again. They aren't easy practices, but if you're serious about writing, then you have to do what you have to do. And these are just my personal practices. They probably won't work for everyone.
BLG