I think it can also do with oversaturation. At some point, you read a bunch of self-improvement books and maybe a bunch of them are saying similar things or many are giving you completely contradictory advice.
You get saturated with the info and trying to decipher what actually applies to you and how to use it, and you can actually ramp up your anxiety or worry further, instead of quelling it.
You’re definitely on point with sometimes needing to put down the book and start working on self-acceptance as you are.
Improvement isn’t a bad thing, but too much focus or worry on it, especially to the exclusion of other things, can be!