If you are working on something you have never done before and this is unfamiliar territory, reach out to 2-3 people who know about this subject than you do, and ask them questions. It might be hard to call them out of the blue and ask, so just ask for 10 minutes of their time. Their advice will motivate and inspire you, and give you the confidence to proceed.
Pro tip: surround yourself with people who won't judge you, and put them on speed dial. Let your friend do the same. This will help you get unstuck many times in the future.
Take a power nap and let your thoughts crystallize. Also, go for a walk, or put yourself in a familiar environment.
If you choose to share your mind with someone else, make sure it's someone who is not going to judge you, and does not want anything in return.
Before starting on a task that you have to do, get into the flow of just getting things done, then focus on the task at hand.
Start by getting something really simple done, like folding your laundry. If you have to, create a list of 10 things that are really easy to accomplish and do those first.
Once you built the moment, switch back to your original task and go with the flow.