I got 4:
"Man's Search for Meaning" by Viktor Frankl. Very famous book. Frankl was a psychiatrist who was a Jew in Austria during WWII. He discusses his time in a concentration camp from his perspective of a psychiatrist. The best book I've ever read. Incredibly significant. Not very long either.
"A New Earth" by Eckhart Tolle. This one is pretty deep but is a fascinating read. He discusses the growing role of the ego in this world and how we must detach from our ego. Very deep though. I haven't read his other book "The Power of Now" yet, but I've heard that one is pretty good too.
Third is
"Letting Go: The Pathway of Surrender" by David Hawkins. Hawkins was a psychiatrist himself. Honestly, despite the deep nature of the topic, I didn't find it to be a difficult read. He explains his methods and beliefs quite well. It is a long one, I believe over 400 pages.
Last one is
"Can't Hurt Me" by David Goggins. He's been on the Joe Rogan podcast a few times. Incredibly inspirational story of a guy who is just an absolute beast. Dealt with child abuse and racism growing up. Was well over 300 lbs and wanted to become a Navy SEAL. Had to lose a ton of weight. Crazy marathon and ultra marathon runner. Goggins has redefined the term "mental toughness" in my view. Couldn't put this one down when I read it.