What does Morrie believe is the cause of people's unhappiness? What does he advise us to do?

Morrie believes that the culture we live in causes unhappiness. For example, the media provides us with images that are impossible to live up to, thus, giving us a sense of defeat within ourselves. Morrie believed that if our culture doesn't work and leaves us feeling inept or unworthy, we need to change it. 

"Well, for one thing, the culture we have does not make people feel good about themselves. We're teaching the wrong things. And you have to be strong enough to say if the culture doesn't work, don't buy it. Create your own. Most people can't do it. They're more unhappy than me - even in my current condition."