The meaning of life
A very difficult topic, already addressed in Aristotle's time.
Many identify it with happiness, not to be confused with pleasure. The latter is ephemeral and tends to fade, whereas happiness is defined as lasting and persistent.
How is it built? There are already suggestions from Socrates, Aristotle, and the Epicureans, and two essential elements can be identified:
1. living virtuously
2. the common good (social, not individualistic, position)
Since I have personally adopted these two principles, I am happier, I live more "fully."