In case it helps.
Instead of simply looking at my daily/weekly to-do list (I call it my Quest Log) I’ve also started a list of things I DID do throughout the day.
It has really calmed me in the face of daunting tasks, being able to look down and say “Actually, yes, I did all those things. My day wasn’t wasted at all.” Even if one of them is “I took a shower.” Everything counts in large amounts.
Stay sane out there, friends.