It's normal to struggle this way with work you don't love sufficiently, which (unless you're lucky) tends to include the work you do for money. Companies have techniques to motivate employees. E.g. your boss or peers will be upset if you don't do something, and happy with you if you do. As a freelancer you don't have that, so the struggle is more visible to you.

Some people can sometimes find types of work that they love so much that this doesn't happen. I have often managed to.