Lifters tend to have problems with cardio because we're used to very short intense work bouts, whereas aerobic training involves long work bouts of moderate intensity. It's just a matter of putting in the time and getting used to it. While Al's approach isn't the worst thing in the world, the best way is to just add a little time to each session you until you eventually can go for an entire hour. Once you can do that, you'll have the aerobic infrastructure in order to add speed. Intervals, what Al is actually describing, are a good way to do this.