Small wins are fuel. Count them out loud so your brain knows the engine is running.

Motivation runs on evidence. When nothing registers as a win, effort starts feeling like it goes into a void, and a mind receiving no feedback concludes reasonably enough that there is no point continuing. Naming small completions is how you keep supplying the signal that something is working.

At the end of the week, say the three things you actually got done, out loud or written down. Not the big remaining task. The finished small ones. It sounds trivial and it materially changes what you are willing to start on Monday.