Good read with many good points. It's about getting power to the ground in the most efficient way possible, and having the endurance to do it for 6+ hours at a time for a few weeks. I think I read in one of Lance's books that to get there, you're looking at about 4000 hours of training per year for the TDF. A 40-hour/week job, with two weeks of vacation is 2000 hours per year for comparison.
Jason