Working on literally anything is kind of like jogging, actually.
First, you have to get off the couch. You have to go from “man, that’d be a lot of work” to “man, that’d be a lot of work, but I’ll feel good when I’ve done it”. Or whatever other reason could possibly motivate you to go out for a jog. Yeah, this is the hardest part. Once you’re up, you need to put on your sports clothes, prepare for the task at hand. Once you’ve done all that, you just put one foot in front of the next and you get going. Backing down after getting into the process is mightily inefficient, so it rarely happens.
But now you’re running. Or working. You’ve got this huge amount of momentum which was a pain in the ass to obtain, but at least you just have to maintain it now. But there’s cute horses in the fields aside the road, and there’s bits of gravel in your shoes. You could stop and interact with all those distractions, but you’ll lose your momentum. You decide against it, but a couple hundred meters later you have to give right of way to an entire parade of cars, so you’re still standing still even though you made all the right choices.
But even then, even after standing still, getting that momentum back isn’t as hard as it was when you were still on your couch. Still a pain in the ass, most definitely, but it could’ve been worse. Half an hour later you’re back home, exhausted. Another half hour later you’re feeling great, wondering why you had so much trouble getting up for this. The next day, you’re stuck to your couch again.
Conclusion: never stop running, at least you’ll die doing something productive.