I've been weightlifting and doing intense cardio. I spend around 20 minutes or less lifting or doing cardio, and I've put on muscle and look fit. I rarely drink soda now, but I still eat junk food weekly and a lot more food than I did a year ago because of muscle growth. I'm not against longer exercises, but I think short duration is best for general fitness since it facilitates muscle growth which raises metabolism, and shortness makes its easier to get in a work-out and stay motivated.
This article explains the benefits of intense cardio.
http://ezinearticles.com/?Why-Intense-Cardio-is-Much-More-Efficient-at-Burning-Fat&id=934858