I too have this problem sometimes. A few things to try:
1.Write a list of tasks, at the top clearly and specifically state a general goal a why. If you can, do the same for each task
2a. Prioritize order
---5 second rule: if you consider doing something for 5 seconds, get off your ass and just do it. Consider writing something on a piece of paper and carrying it in your pocket to physically help remember the five second rule
---Pomodoro Method: A timed system for work break intervals (lots of apps for this)
---r/theXeffect :Basically a grid for visually tracking goals on a day by day basis, effective though(also apps)
4: Keep these somewhere you will check and update everyday, preferably as a physical piece of paper
"There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self." -Hemingway
Just try to do better than you did yesterday