This post comes after A 28-second Tip On How To Get Stuff Done, but you totally don't need to read that first.
This article is not up to my usual standards. I would've put this as a quick take, but the format of a quick take is a bit wonky for this article.
Realize that the sooner you finish your task, the more time you spend not feeling guilty about it and (usually)the same amount of time doing it.
Write down what you have to do somewhere, such as the notes app, reminders app, or something else. This will help lower the number of things you forget to do.