There are three big distractions that keep us from finishing our organizing projects. Here they are, and here we can figure out how to get around them:

we stay on task. The project we started working on gets finished more quickly and deliveries around the house don't take away whatever time we've already set aside. If you have someone eager to help with your project, have them play delivery person whenever you come across an item to go elsewhere.
2) Listening to something else. TV, radio, someone else in the house. It doesn't really matter what it is that has caught your ear if it makes you stop what you're doing. If you know you can't concentrate with background noise, turn off the TV, the radio, your phone, all the things that make some kind of noise. It's only temporary while the project's in full swing. Likewise, if someone else is in your space (spouse, kid, roommate, co-worker), let them know that you can't be bothered for "X" minutes. After that, you're all ears!
3) Someone making you stop. This is similar to the previous distraction, but can also include more. An appointment arises in the middle of your project. A neighbor stops by unexpectedly. The dog throws up. Who knows what it might be, but it's made you come to a complete halt. We can prevent some of this by paying attention to our calendars and marking down anything pertinent. Other than that, do your best to stay on task and explain, politely, that you're in the middle of a project and would love to set aside time later to catch up.
Now you can stick with it!