Learn to program. ;-)
Seriously, there are a bunch of reasons why coders turn down a startup:
1.) Not enough compensation. If you're paying them cash, you have to pay them market rates. For a bright but junior programmer, that's minimum $55-60K/year. salary in most of the tech hotspots. For someone experienced, figure at least $100k/year. If you're looking for hourly contractors, expect to pay at least $75/hour for anyone decent. If you give them equity - well, I personally would not join a startup for less than 20% equity, and I suspect many other technical founders have similar minimums. Actually, the only reason my current startup got away with so little (I'm getting 25%) is because it has 5 founders, and nobody else has more than 25%.
2.) Boring idea. Good programmers like to work on interesting problems. I joined my startup because it was in a problem domain that I waste a lot of time in anyways, I knew the area, and it'd let me try some cool stuff that I didn't know if I could do, but it'd be fun as hell to try.
3.) They don't trust you. Techies have a natural aversion to business-type people. Be straight with them, always. The second they think you're trying to bullshit them, they'll walk away.
4.) They don't think you add much value. Ultimately, it'll be the techie building the product. They need a reason why working with you beats building the product on your own. Usually, your best bet is to have a large personal network, or good people skills, or the ability to sell something. I don't think it's necessarily true that techies can't be good with people, but in my experience, I can't code and be good with people at the same time, so have a cofounder with people skills has been a big win for me.
Remember, if you're founding a technical startup, you want the best coder you can find. He'll usually be young, because good experienced coders typically have families and will not work for stock, and you generally can't afford the $150K/year that they'll cost you. Don't try to skimp and get cheaper labor - lots of companies tried that in the dot-com bomb (notably Value America), and they almost universally went out of business. Average coders cannot hit the high notes; you need to hit the high notes as a startup, because all of the middle ground is taken.
In my case, I met my cofounder at Homecoming. We'd lived across the hall from me sophomore year, so I went over to talk to him and see what he was doing. Turned out he was working on a startup in a field I was interested in. He introduced me to the other cofounders afterwards (2 of which I already knew from college). I didn't actually join until several months later, when their initial choice for a technical founder quit, but he kept my name in mind.