What is Frankl theory of logotherapy?

Developed by Viktor Frankl, the theory is founded on the belief that human nature is motivated by the search for a life purpose; logotherapy is the pursuit of that meaning for one’s life. Frankl’s theories were heavily influenced by his personal experiences of suffering and loss in Nazi concentration camps.Jul 2, 2015
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.

http://www.pursuit-of-happiness.org/history-of-happiness/viktor-frankl/