I too find that sometimes I need to tell myself that I am not going to start that new project I want to do until I get this one DONE! It keeps me going. I also organize the project very precisely. I cut ALL the pieces I need so there is no, "I can't make those blocks now because the pieces aren't cut." type of thing.
Lay all the parts out how they need to be done. Stack all your strips by light, dark, color or however you're doing it, and keep them out right there by the sewing machine. Don't make it so that you have to get it out to work on it.