Viktor Frankl is a renowned psychologist and survivor of Nazi concentration camps.  His book, “Man’s Search for Meaning”, sold two million copies.  In it, he expounded “Logotherapy”.

Logotherapy in a Nutshell (Quotes)
Striving to find a meaning in one's life is the primary motivational force in man, not a "secondary rationalization" of instinctual drives (Freudian theory).  That is why man is even ready to suffer on the condition that his suffering has a meaning.

People have enough to live by but nothing to live for; they have the means but no meaning.

Suffering ceases to be suffering at the moment it finds a meaning, such as the meaning of a sacrifice.  These sufferings are even the things of which I am most proud, though these are things which cannot inspire envy.

What man needs is not a tensionless state but rather the striving and struggling for a worthwhile goal, a freely chosen task.  Everyone has his own specific vocation or mission in life to carry out a concrete assignment which demands fulfillment.  Everyone's task is as unique as is his specific opportunity to implement it.

In the same way fear brings to pass what one is afraid of, likewise a forced intention makes impossible what one forcibly wishes.  Happiness cannot be pursued; it must ensue from the potential meaning inherent and dormant in a given situation.

The more one forgets himself - by giving himself to a cause to serve or another person to love - the more human he is and the more he actualizes himself.

Humor is another of the soul's weapons in the fight for self-preservation. It is well known that humor more than anything else in the human makeup, can afford an aloofness and an ability to rise above any situation, even if only for a few seconds.

When we are no longer able to change a situation, we are challenged to change ourselves…  Between stimulus and response there is a space. In that space is our power to choose our response. In our response lies our growth and our freedom.

The true meaning of life is to be discovered in the world of experience rather than within man's own psyche as though it were a closed system. Our answer must consist, not in talk and meditation, but in right action and in right conduct... Taking the responsibility to fulfill the tasks which life constantly sets for each individual.