Limits on Life?

Today, we've discussed living for hundreds of years. Would we really want to live that long? Someone mentioned the current overpopulation problem we have in the world. I would imagine that it would continue to be a problem if we lived for hundreds of years instead of just living for 70-80 years. But what would we really need in order to live so much longer than we do now? Would we need some type of physical regeneration capability? How will we fight off cancer or other diseases? Could our economy survive if we lived longer? Would we have enough natural resources to sustain our growing society? This topic really makes me think. No one wants to die, but what if dying is what is best for us?