One of the hardest aspects of work for me is when I know I have a hard task to do. I’ve found some psychological trickery that works well on me that might be useful for you too.
I’m a big fan of the Pomodoro Technique. There are lots of ways to implement it, but the basic premise is to work for 25 minutes, then take a five minute break. After four 25 minute work periods then take a longer break.