It was a dangerous move – seemingly foolish, and fraught with risk. Failure could mean injury and being dropped from the training. Without hesitation the student slid down the rope perilously fast. Instead of several minutes, it only took him half that time and by the end of the course he had broken the record.

If you want to change the world sometimes you have to slide down the obstacle head first.

During the land warfare phase of training, the students are flown out to San Clemente Island which lies off the coast of San Diego. The waters off San Clemente are a breeding ground for the great white sharks. To pass SEAL training there are a series of long swims that must be completed. One is the night swim.

Before the swim the instructors joyfully brief the trainees on all the species of sharks that inhabit the waters off San Clemente. They assure you, however, that no student has ever been eaten by a shark – at least not recently. But, you are also taught that if a shark begins to circle your position – stand your ground. Do not swim away. Do not act afraid. And if the shark, hungry for a midnight snack, darts towards you – then summon up all your strength and punch him in the snout, and he will turn and swim away.

There are a lot of sharks in the world. If you hope to complete the swim you will have to deal with them.

So, if you want to change the world, don’t back down from the sharks.

As Navy SEALs one of our jobs is to conduct underwater attacks against enemy ship-ping. We practiced this technique extensively during basic training. The ship attack mission is where a pair of SEAL divers is dropped off outside an enemy harbor and then swims well over two miles – underwater – using nothing but a depth gauge and a compass to get to their target.

During the entire swim, even well below the surface, there is some light that comes through. It is comforting to know that there is open water above you. But as you ap-proach the ship, which is tied to a pier, the light begins to fade. The steel structure of the ship blocks the moonlight, it blocks the surrounding street lamps, it blocks all am-bient light.

To be successful in your mission, you have to swim under the ship and find the keel

– the centerline and the deepest part of the ship. This is your objective. But the keel is also the darkest part of the ship – where you cannot see your hand in front of your face, where the noise from the ship’s machinery is deafening and where it is easy to get disoriented and fail.

Every SEAL knows that under the keel, at the darkest moment of the mission, is the time when you must be calm, composed – when all your tactical skills, your physical power and all your inner strength must be brought to bear.

If you want to change the world, you must be your very best in the darkest moment.

The ninth week of training is referred to as «Hell Week.» It is six days of no sleep, con-stant physical and mental harassment, and one special day at the Mud Flats. The Mud Flats are area between San Diego and Tijuana where the water runs off and cre-ates the Tijuana slues, a swampy patch of terrain where the mud will engulf you.

It is on Wednesday of Hell Week that you paddle down to the mud flats and spend the next 15 hours trying to survive the freezing cold mud, the howling wind and the in-cessant pressure to quit from the instructors. As the sun began to set that Wednes-day evening, my training class, having committed some «egregious infraction of the rules» was ordered into the mud.

The mud consumed each man till there was nothing visible but our heads. The in-structors told us we could leave the mud if only five men would quit – just five men