Ask HN: How do I find the right co-founder?

I'm just graduating college this week. I have an idea that I'm ridiculously excited about. I'm already working on it full-time, and I can build and launch the product by myself without a co-founder.

That said, I realize that I need a co-founder for a variety of reasons. I've already raised money for a previous start-up of mine, and I know firsthand that the start-up grind is simply too hard to do it alone.

I have a very particular idea in mind for who I would want as a co-founder, but nobody I know meets all the criteria. I want somebody with intelligence, work ethic, and integrity, and with a healthy appetite for risk.

I feel like someone in their 40's who desperately wants to get married and is thinking about whether or not they want to settle. I understand the benefits of having a co=founder versus not, but I also realize there are huge risks in picking the wrong person.

What should I do? And where should I look?