There is no one meaning to life. For each person it may be different and may change over time. The spiritually health, thoughtful person seeks meaning daily, according to Viktor Frankl in his book Man's Search for Meaning, a psychology classic in a new edition with a foreward by Harold S. Kushner.
The first half of the book describes Frankl's experiences in a series of concentration camps during World War II. He observes that secure, thoughtful people exhibited more ability to survive than the physically strong. He also describes how prisoners found ways to humanize their conditions. He claims that individuals are responsible for their own mental attitude and can find hope within themselves no matter what hardships they face. Doing so is necessary for survival.
The second part of the book is about logotherapy, Frankl's method of psychiatry. He explains that Freud emphasizes the past while he points to the future, asking clients what is the meaning of their continued existence.
While Man's Search for Meaning is a short book, it is better to read over the course of several days to give the message more time to become clearer.
Frankl, Viktor E. Man's Search for Meaning. Boston: Beacon Press, 2006. ISBN 0807014273