There is one primary difference, though, between time and money. We can choose not to spend our money; we can save it, set it aside, or invest it. But we can’t do that with time. We’re going to spend every minute we have. Whatever we choose to spend it on, that’s the value it has for us. That also means we’re not spending it on anyone or anything else. Once it’s spent, it’s gone. That’s opportunity cost. We will spend every hour that we have. If we don’t determine where we’re going to spend it, then someone else will decide for us.