Not a founder myself, but the people I've been scheming with are either college friends or co-workers from other startups. IMO, working at a startup great potential source of future teammates (but I rarely see that mentioned around here).
I met my first co-founder in college and my second one through the local tech scene. In both cases I made sure that these were people that I could get along with before anything. Skills are picked up along the way but if you don't work well together it's going to be a painful ride.
Co-founding is like getting married, except without the sex.
i personally met my co-founders through super smash brothers: melee and during college (separate occasions). we've been good friends for over 4 years, most likely due to our similar interests.
i agree with your post that you should not rush or force yourself to find a co-founder. for those sole founders, i recommend attending mixers to meet people with similar interests and approaching people without the intent of finding a co-founder. make true friendships instead; your co-founders/life partners will follow.
