They explained their jobs to me but I was not listening.
Don't you care about what people say?
Not particularly, I had more important things to do.
Not listening to people's interest in their own jobs is inconsiderate when they are trying to share with you. Put aside your own desires and be there with them in the conversation.
Why should I?
Think about how you'd feel if you were telling someone about yourself and they didn't listen to a word you'd said. Then think about the opposite, how good it feels when people hear you, show interest and ask questions about what you said.