It’s fairly easy, and a construct of existentialist philosophy.
There are two branches of explanation to the meaning of life. These are broken down into consequences and content. Consequences would be an expectation that life is building up to an ultimate goal, or that anything a human being does has an inevitable consequence and meaning. On the other side is content, where the meaning is within life itself.
Now under each of these categories there is a subjective and objective explanation as to the meaning of life.
This is best described in religion. Instead of confronting the meaning of life, or looking for it in consequence that can be measured or observed, we look beyond our own world and explanation into the heavens. Thus the meaning of life is not discovered or attained until death, and then it is only subject to a deity or other religious belief. The problems with this are the same old problems with religion when discussed in a philosophical context. There is the problem of God and the status of God as evil or good, the notion that one must die to know, and the lack of any kind of reasonable evidence in our everyday experience.
Rocks. This is how my professor in existentialist philosophy put it. Objectively, that is using evidence in the real world, and observed logical conclusions, the consequences of our actions are just a different pattern of atoms. If I decide to throw my pencil across the room, then it is across the room. If not, then it is still here. The consequence of such actions, in context of the meaning of life, is that when all is said and done and billions of years have passed, rocks in outer space may be in a different place.
The meaning of life is whatever makes me happy and whatever I see as valuable to me. This sounds like a reasonable claim. However, it is not. This is a leap away from the question, avoiding the meaning of life by assigning value to meaninglessness. It is the path of empty desire. Self fulfilling and is more of a distraction than anything else.
Meaning comes from everyone around us, and is evaluated objectively and logically. The ultimate truth of which comes with death. Everyone dies. Therefore the one objective and most reasonable answer for the “Meaning of Life” is death itself.
Makes you feel all warm and fuzzy, huh? Those existentialist are sure the life of the party.