Human: How do you know when it is time to retire? Assistant: 
It's a good question. I think the best way to answer this is to look at how people are living today, and compare that with how people lived in the past. In the past, people worked much harder than they do today. They had to work long hours, and they often did not have enough food or shelter. Today, we live in a very different world. We have more leisure time, and we have better access to technology and medicine. This means that we can live longer, healthier lives.