The thing that's rarely answered sufficiently is the question of how to find a good co-founder. The answer is often "Find someone you worked with or went to school with that wants to start a company with you"
The thing is that there are a limited number of people to pick from based on these criteria. Out of these you have to find someone that's smart, gets things done and has the stamina to do a startup. For most people this amounts to a grand total of zero people.
I've done startups where I slacked on the co-founder criteria, thinking "Oh he's not the smartest guy I know, but he's a hard worker" or "he knows everything there is to know about this domain, but he's not 100% motivated" and I've been disappointed every time.
If you don't have a perfect match I'd recommend going it alone.
+1.
I'm doing a startup with a friend (I'm engineering, he's business). And I know a bunch of smart, capable people through my 10 years of doing startups in Silicon Valley.
I think finding smart, capable people is the easiest thing to do. Harder than that is finding people who want to do a startup (as many of my peers, now with 10 years experience, get comfortable paychecks). Harder than THAT is finding people who want to try to do a startup that's not funded. Harder than THAT, is finding all of the aforementioned stuff and someone who's has the burning desire to work in the space/industry that you think could use a new solution.
The thing I've realized is that when it's your idea, you see the potential of what could be. When you approach others, they only see what can go wrong with your idea. And, admittedly, you're trying to get them to buy into a vision that you've thought about endlessly while they've only had the pitch you gave them over lunch.
It's tough. Paul Graham's article about entrepreneurs as animals is right on.
I think you're missing the personality differences. Several of the ventures I've been a part of I joined simply because it looked like such a challenge. I enjoy pushing the limits of my mind, of what I know and of what I can do. This isn't a "do it the hard way because it's more fun", it's finding that simple, elegant solution to the impossible problem, or like a touch of red pepper in spaghetti sauce to give it that tiny kick it needs to be perfect. If you're trying to sell people on your idea to be co-founders, they aren't the right person. If you tell them and they start talking in plans and ideas and acting like it's their idea, too, you have a good co-founder.
The thing is that there are a limited number of people to pick from based on these criteria. Out of these you have to find someone that's smart, gets things done and has the stamina to do a startup. For most people this amounts to a grand total of zero people.
I've done startups where I slacked on the co-founder criteria, thinking "Oh he's not the smartest guy I know, but he's a hard worker" or "he knows everything there is to know about this domain, but he's not 100% motivated" and I've been disappointed every time.
If you don't have a perfect match I'd recommend going it alone.