I wrote an essay a while ago on motivation that overlaps with your observations, so I just wanted to share 😄. In particular, why the idea of "the cure is to push through and do lots of stuff anyway" is silly:

https://docs.google.com/document/d/1CyHvCwWh_BwukwNE-y61oBCjztD3_IVOGWrJo8qQ_pI/edit