I don't have a good fix for like... solving it in the sense of making yourself do it, but at times I think it's sometimes helpful to do bullet point prep where you don't write more than your session goal and a few bullet points with the major ideas to remember- plot threads, NPCs, enemies, etc.

I think it's usually possible to riff a decent session off of that, you can reassure yourself that you haven't been left with nothing, and if you want to revisit prep, you have a decent starting point to work from. It's helpful to me when I feel like I don't have a lot of capacity, at least.