I can so relate to this!
First, figure out your most productive hours to dedicate solely to your work. For example, I know I'm most in my focused flow first thing in the morning until about 2 o'clock (cell-phone away, work time only), and for about an hour or two I do creative planning at night to project for the following day. Secondly, write down your goals !!!

Third, and possibly most importantly, take scheduled breaks to avoid burnout. Some neck rolls and simple stretching to get back into your body and away from a screen for just 5 minutes every hour or two can do wonders!

Lastly, if you feel you are wasting time and unfocused, simply step away and do something more productive with your time. Sometimes we try to push through and it creates a cycle of writers block and frustration. Freshness and a state of calm will always be the most valuable setting for creativity to flow!
Thanks for the post, got me reflecting on my own structure/lack thereof. Giving you a follow friend :) Blessings