Join a gym. That way you can lift in addition to your cardio routine, plus if you're like me, paying for it provides extra motivation to go regularly.
Rather than chocolate milk, get some chocolate flavored whey protein and mix that with milk for breakfast. Plan9 has excellent advice. It's pretty much identical to what a friend of mine (5'8", 155lbs, can bench 250+) tells me (5'8", 150lbs, was a complete wimp) to do. So far it's working incredibly well.