For long projects, momentum can be the difference to success and failure. Once you become burned out, or too frustrated to continue, the chance of reaching your goal begins to rely on pure chance. A great way to get past this, then, is to gain momentum early on to carry you through those roadblocks.
To do this, break your goal into small steps, and make the steps extremely easy to complete. Each day one of the first things I do is make a To Do List for that day. Some of these tasks will take only a minute or two each, and I make sure to knock them out immediately. Take out the trash? No problem. Flip the mattress? Done.
These tasks won't ever be enough to turn my day into a productive one, but they get me going. Once I have 2 or 3 items moved to the 'Completed' side of my list, I start getting excited to move the next one, and then the next one, until the list is empty.
I've also found that there are a couple of side benefits to this method. First, it's great for building habits. Every day I have 'Take supplements' and 'Work Out' (which is more detailed, but you get the idea) on my list. Because they are in front of me throughout the day, there is little chance I can forget them. Smaller habits, such as flossing or taking vitamins/supplements, can easily be your early win each day.
The other benefit is that things I consider low priority are actually getting done. Rather than wait until tomorrow to do laundry, I now have an incentive to do it today because it's so easy. I spend less time playing games on my phone or checking TheChive, and more time overall being productive. So far, these low priority tasks are simply being replaced with more low priority tasks. I'd normally have to set aside half a day or more to clean out a closet, but now I'm doing one or two items per day, and the project is complete within a few days or weeks.