Cooperation is one of the primary ways resources get allocated in society. I've got an hour of time, and am good at repairing computers. You've got an hour of time, and are good at fixing cars. You need a computer repaired; I need my car fixed. We cooperate, trading something we have for something we want more. The "more" is important here. Each of us allocates the resources we control, starting with our own time. If, right when you want your computer fixed, I'd rather sleep or work on someone else's computer, you will have to find someone else to repair your computer. Similarly, if you want to sleep or work on some else's car when I need my car fixed, I will have to find some other way to get my car repaired. Neither of us can use force to get what we want. Or even to get what we need.