If writing documentation feels like hitting a wall, the scope of what you are trying to document is probably too big. I try to treat docs like atomic commits. Instead of waiting until the end of a massive feature branch, I write a single paragraph in the README the moment a core architectural decision is made. If you document the "why" while the context is still fresh in your head, it takes 30 seconds. If you wait until Friday afternoon, it takes two hours of mental backtracking.