When our government decided to commit ground forces in Afghanistan, I wondered what type of training it would take to keep these soldiers in such superhuman shape -- especially to endure the cold, harsh terrain and high altitude. Both of my grandfathers served in the U.S. Army air forces in World War II, and my father was an Army Ranger, so I grew up aware of the military's rigorous conditioning. But when I investigated the training regimen of one of our country's special forces, the Navy SEALs, I found out what it takes to be one of the best fighting forces in the world -- and it's not your average "boot camp" class at the gym. Every military recruit goes through eight weeks of basic training, but that's a walk on the beach compared with the intense physical and mental training required of the special forces.

The Navy established SEAL (sea, air and land) teams in the '60s to conduct clandestine operations. The SEALs' brutal 26-week endurance test is conducted mostly on the beach in Coronado, Calif. "This is the toughest military training in the world, and it's done that way on purpose," Navy SEAL Cmdr. Gary Stubblefield told the authors of U.S. Special Forces: Airborne Rangers, Delta & U.S. Navy SEALs. "If you take away the risks that come with the training, you take away the mental and physical risks that come with actual combat."

Candidates must be male, in the Navy and no older than 28. They also must score high on written and physical-fitness tests.

Phase 1 of training is an eight-week program of running, swimming, calisthenics and trips around the "O" (obstacle) course; the program grows more difficult as the weeks progress. The O course resembles a gigantic sandbox with lots of "play" equipment, including telephone poles of various sizes to dash across, nets and 25-foot walls to scale, and barbed wire to crawl under. The swimming requirements include 1- and 2-mile bay, ocean and pool swims with fins. The drill instructors increase the intensity daily, pushing trainees to improve their time in the water while avoiding hypothermia. Men inevitably drop out, are removed because of injuries or ring "the bell" to signal that they can no longer endure the training.

Sound exhausting? Well, that's just Phase 1. We haven't even gotten to Hell Week yet.

Hell Week starts just before midnight with an instructor waking trainees with the sounds of shots from a machine gun. The trainees then begin 5 1/2 days of constant activity, including more running, swimming and boat drills. During Hell Week, the focus is on teamwork: Teams of trainees are required to lift and maneuver logs weighing 400 to 600 pounds. Working as a team, they have to hold the logs overhead and do sit-ups with the logs on their chests.

During Hell Week, trainees consume about 7,000 calories a day -- and they still lose weight! They get a maximum of four hours of sleep for the entire week. This is the utmost test of physical and mental toughness; it's not unusual for trainees to start to hallucinate after about four days.

Hell Week survivors go on to the seven-week Phase 2, which focuses on diving operations. Physical training continues, and trainees are expected to lower their times for the 4-mile run, O course and various swims. Phase 3 is land warfare, which lasts 10 weeks. Physical training peaks here, and trainees must complete (among other things) a 4-mile run in boots within 30 minutes as well as a 2-mile ocean swim with fins in 75 minutes.

Next it's off to jump school, which includes a week of physical conditioning and a week of parachuting, followed by Jump Week. Five jumps are required: three "Hollywood" (daylight) jumps without combat equipment, one night jump and one jump with a loaded rucksack and weapons container.

Last, before trainees can become bona fide SEALs, they're assigned to teams for six months' probation (and yes, they still can fail at this point).

I keep a rather push-the-limit workout schedule -- weight training, rock climbing, running (about 20 eight-minute miles a week), yoga and skydiving, among other things -- but I am humbled by the level of fitness required by SEALs. These guys are the real deal.

The SEALs' training regimen stresses discipline and teamwork, and it relies on old-fashioned exercises that work every part of the body -- nothing new there. But the military's belief in the relationship between a fit body and an alert mind is perfectly in step with today's fitness trends.

I now understand why some of these guys have a bit of an edge. It comes with the territory, and it's earned. If I could make it through their training, I'd carry that edgy attitude, too!