I'll use the "fear is the mind killer" [1] quote when I'm upset or anxious quite often. I really should add this one to my arsenal as well. I've never thought of Dune as a self-help book but I might now. Weirdly enough I'm also currently re-reading it, after watching the miniseries due to quarantine, and I'll try to find more things like this during my reading.
[1] “I must not fear. Fear is the mind-killer. Fear is the little-death that brings total obliteration. I will face my fear. I will permit it to pass over me and through me. And when it has gone past I will turn the inner eye to see its path. Where the fear has gone there will be nothing. Only I will remain.”
"Start where you are, use what you have, do what you can".
I love the attitude it conveys. It's not an affirmation, but a call to action. It got me out of overwhelming situations when I was alone and far from home.
"I am not afraid. I am not afraid because if I let myself get too scared I might not be able to do what needs to be done. And I'm not the type of person who backs down. I am the type of person who does the right thing, even if it's hard. Right now, the right thing is to [x]. And even if it doesn't work, I'll just do the next right thing, and the next, and the next. I'll keep on trying until I figure out a way."
I do this too! I like to write the whole litany against fear out a few times to fill up a page. I find this helps me identify the root of whatever I am currently feeling anxious about. Once you identify the fear, then it can be addressed directly.
[1] “I must not fear. Fear is the mind-killer. Fear is the little-death that brings total obliteration. I will face my fear. I will permit it to pass over me and through me. And when it has gone past I will turn the inner eye to see its path. Where the fear has gone there will be nothing. Only I will remain.”