How Long Should One Wait for Someone?

A friend of mine invited me to go jogging with him.
I accepted thinking it would be nice to have company while jogging for once.
I got to our appointed place at the appointed time, right on the dot and he was nowhere to be seen, so I waited. 10 minutes go by and he's still a no show. I begin my warm-up. It is at this moment that I began to think 'how long should one wait for someone?'

In this case, since it was just a jogging session that I could do alone, I waited 30 minutes and started without him. (It turns out, something came up and he couldn't go as planned.) But what if the situation was something more important? How long should one wait for someone?

I don't really know, I guess it depends on how important. If your life and happiness depended on it, I guess one could wait forever. What do you think? How long will/can you wait?