"No writer has ever lived who did not at one time or another get stuck." Jaques Barzun.
What he's talking about is writer's block and the need for discipline. I had a long time writer's block and I knew the cause. I was working 13 hour shifts as a nurse and frankly I was drained physically and mentally. Sure I wrote a few bits and pieces but nothing that went anywhere or connected to anything.When the time came to leave this demanding job and begin to write again, I found it hard to do more than bits and pieces.
What I finally did was go back to the beginning and start with a plan. I set myself a low goal of words on a story I'd organized with many pages of notes. First 500 words a day and I refused to stop until I had these words. Discipline is what kept me moving forward. Now I do 2 or 3000 words a day. Sometimes i get stuck. I force myself to write out the plan of the story and suddenly I can write again.
So discipline is the word to remember. No one is forcing you to write and no matter the reason for writing once the flow begins put the words down. Remember that the discipline will allow you to revise and make the story a great one.
Also remember the words from the opening sentence. You are no different from any other writer. When you're stuck try a little discipline or some other trick that works for you to push beyond that gap.