Which Book would you recommend to someone who wants to fight his negative thoughts and be more resilient/optimistic?

Hi y‘all.

I‘ve been in work life for around two years now and while I mostly get my tasks done in a sufficient way, I always get confronted with negative thoughts once I deal with a problem I do not have a solution for right away like “I can’t do this” or “How am I supposed to know”.

I also get demotivated quickly and just want to work on my mindset and try achieve being more optimistic in general.

My therapist generally recommend practicing mindfulness/meditation, so books in that area would also be highly appreciated.

Thank you very much.