I was like you when I began quilting, didn't even think about another quilt until the one I was working on was finished. Then I found quilting message boards and learned all about UFOs, WIP, PIGs, etc. and began having too many projects going at the same time. When making a large quilt it is hard to keep my enthusiasm up about it and my mind does wander thinking about other projects, colors, designs but I try to stick to it or I'd never get anything finished.
Rule now is that it's OK to have 2 or at the most 3 projects in the works at the same time but they have to be kept where I will see them or I'll forget about them and add more projects. Wish me luck sticking to that rule. May in Jersey