I simply break down huge tasks into small, achievable pieces. Like I am now working on editing 100 pages article, I set myself up to at least finish 1-2 pages per day. That sounds silly but it works. Because once I've finished 2 pages, I tended to keep on working to finish up to 5-10 pages. It's like tricking my brain into working mode. Once that mode is on, things are a lot easier.