According to my big running book, one of the biggest problems in training for a long run is the time it takes from all the other things you could be doing, such as spending time with your family. My wondefrul wife and the kids are very supportive: whenever I stagger in the front door, I am greeted with "how far did you run, Dad?", and "Daddy, did you run FAST?" from junior.
The more one can combine running with other things, though, the better. Hence my plan this morning: to run Tom to school, literally. He was cycling, and I was trying to keep up. It's only 2km there, so it's good speed training, but I was too slow for his liking, especially since it's downhill. Uphill on the way back was a little slower, but it's a virtuous way to start the day.