Man’s Search for Meaning is a 1946 book by Viktor Frankl chronicling his experiences as an Auschwitz concentration camp inmate during World War II, and describing his psychotherapeutic method, which involved identifying a purpose in life to feel positively about, and then immersively imagining that outcome.
Two short animated book summaries:
Viktor Frankl interviews:
Finding Meaning In Difficult Times
Unlocking the Power of Your Mind – Viktor Frankl & Joe Dispenza video clips