Roy Baumeister has written an interesting piece recently for Aeon Magazine on the role of meaning in a human's life. In the first section, he describes the differences between happiness and meaning since they are often used interchangeably but are really quite different.
The first had to do with getting what you want and need. Not surprisingly, satisfaction of desires was a reliable source of happiness. But it had nothing — maybe even less than nothing — to add to a sense of meaning.
...The second set of differences involved time frame. Meaning and happiness are apparently experienced quite differently in time. Happiness is about the present; meaning is about the future, or, more precisely, about linking past, present and future.
...Social life was the locus of our third set of differences….Simply put, meaningfulness comes from contributing to other people, whereas happiness comes from what they contribute to you.
...A fourth category of differences had to do with struggles, problems, stresses and the like. In general, these went with lower happiness and higher meaningfulness.
...The final category of differences had to do with the self and personal identity. Activities that express the self are an important source of meaning but are mostly irrelevant to happiness.
With the differences explained, he then describes what he calls "the four needs of meaning."
The meaningful life, then, has four properties. It has purposes that guide actions from present and past into the future, lending it direction. It has values that enable us to judge what is good and bad; and, in particular, that allow us to justify our actions and strivings as good. It is marked by efficacy, in which our actions make a positive contribution towards realising our goals and values. And it provides a basis for regarding ourselves in a positive light, as good and worthy people.
Drilling in on the second need, Baumeister writes more specifically on how a meaningful life has values. We describe what Baumeister refers to as "values" as social norms. One of our motivating conjectures is that social progress cannot be explained by improvements in technologies alone. It is the co-evolution of social norms, technologies, and formal laws that sustains progress.
The second need for meaning is value. This means having a basis for knowing what is right and wrong, good and bad. ‘Good’ and ‘bad’ are among the first words children learn. They are some of the earliest and most culturally universal concepts, and among the few words that house pets sometimes acquire. In terms of brain reactions, the feeling that something is good or bad comes very fast, almost immediately after you recognise what it is. Solitary creatures judge good and bad by how they feel upon encountering something (does it reward them or punish them?). Humans, as social beings, can understand good and bad in loftier ways, such as their moral quality.
In practice, when it comes to making life meaningful, people need to find values that cast their lives in positive ways, justifying who they are and what they do. Justification is ultimately subject to social, consensual judgment, so one needs to have explanations that will satisfy other people in the society (especially the people who enforce the laws). Again, nature makes some values, and culture adds a truckload of additional ones. It’s not clear whether people can invent their own values, but some do originate from inside the self and become elaborated. People have strong inner desires that shape their reactions.