When I eat out at a restaurant, I rarely order an appetizer even when it is offered. Instead, I begin with the entree. This may be a good strategy for dining, but in time management, sometimes it is best to begin the process with a nibble.
If you start your major project with a "appetizer," it will seem less daunting than taking on the entree. An appetizer isn't a diversion separate from the meal, rather it is the first, smaller part of it. By adopting this philosophy to your project, you can start with an initial piece of what you need to do before diving in. Think of it as preparing an outline before you begin writing or assembling the tools before you begin a renovation project. It moves you forward without overwhelming you or filling you up.
Having an appetizer also motivates you to start, and as I have said many times, beginning is the hardest part of doing anything. So the next time your to-do list contains something that looks like a main dish or even multi-course meal, focus on the appetizer first and see if that strategy doesn't easily slide you right into the meat of the project.