At any one time I'd have a dozen projects all being worked on, none of them ever being finished. As I got older I made a rule never to start a new project unti

At any one time I'd have a dozen projects all being worked on, none of them ever being finished. As I got older I made a rule never to start a new project until the old project is finished. As I've switched, I've noticed the motivations have changed. The last 20% of any project is un-fun work. All the excitement is gone and all that is left is tedium. This is when your eyes start wandering to other projects. It's addiction. You are addicted to the fun part, and when it's no longer fun you start looking for you fix somewhere else. The trick is to change your addiction. Force yourself to finish a project. Get addicted to the sense of accomplishment instead of being addicted to learning something new and exciting. If you only care about the learning and not the doing, you'll end up reading wikipedia all day, every day.