There's no right answer to this question. It depends on who you ask. It is somewhat individual based, but I would posit that the meaning of life is more group based. Specifically, religiously and "ism" orientated.
For example, the meaning of life to Christians is love. That sounds trendy and lame, but it is supported through Biblical scripture. The new testament summarizes God's law by saying that man's (people/believers) goal is to love God above all else and love your neighbor as yourself.
The meaning of life for a different group of people can be boiled down to "isms." I can't possibly list all of them, but I'll go for a few.
Materialism -- To a materialist, the meaning of life is squarely focused on gaining and obtaining material possessions. To this person, true happiness and meaning is found through owning stuff. He who dies with the most toys . . . wins.
Hedonism -- A hedonist's meaning of life is in finding pleasure. Whatever feels good, do it. Nike's slogan nicely relates to this philosophy on the meaning of life. "Just Do It."
Existentialism -- This one says that reality is meaningless. There isn't an afterlife either. It's concerned with the here and the now. Abraham Maslow has a pyramid that ties in with this philosophy. The pinnacle of it is "self-actualization."
"the desire for self-fulfillment, namely the tendency for him [the individual] to become actualized in what he is potentially."
While the above may seem confusing, it emphasizes an aspect of carpe diem. The meaning of life to an existentialist is to reach their full potential and to do so sooner rather than later. Why wait? Seize the day.