"Always eat your dessert first"

Meaning, when you feel overwhelmed by a huge task or a long list of tasks in front of you, start with the easiest, smallest and most pleasant parts. That way you overcome inertia and the feeling of standing in front of a huge, looming mountain, and get in the groove.

Once you've started, the next task on the list is just a little bigger than the last, which you've just successfully completed. That way you can get a lot done, step by step.

When only the biggest and most difficult tasks are left, you can break them down into tiny steps (don't "clean the house", just "pick up this one thing and put it away"). Again, do the easiest steps first, and celebrate each one as a thing you've just successfully accomplished.

Some people say you should start with the hardest stuff to get it behind you, but I have ADHD and trying that just keeps me from starting anything at all.

On a related note, don't write To-Do lists.
They're a devious trick by your brain to procrastinate. You already know a dozen things that need to be done at any given moment, so instead of writing a list, just do one of them.