Make a plan to breakdown the steps to be completed by a time line.
Example: When I did the NaNoWriMo writing challenge last year to complete 50,000 words written by the end of the month I divided the number of days into 50,000 and came up with 1666.67 ( rounded off) to write a day in order to complete on time.
However last year the Library stated us in Canada a week later , thus we were doomed to failure as we were already (1666 X 7 days = 11,669 words lost).
I stepped my writing up to 3000 per day and did that by doing 1500 in the Am and 1500 words in the late evening. It was tough going but I did it and won my winners T shirt but actually all of us won ( our drafts for a story).
Bottom line things can be completed , for me anyways by making a plan and sticking to it.