A lifeguard is a specially-trained and certified bodyguard to the President of the United States. Originally created by an act of Congress in 1864 to save drowning government officials when they waded too far into the deep end at the Congressional Pool, Lifeguards evolved into the elite force of protectors of the President. At the same time, however, they developed a horrible aversion to water, finding it beneath their dignity. Nowadays, their devotion to the President of the United States ("POTUS") is seconded only by their disgust for water. (When the president is at risk of drowning, Aquaman now has sole jurisdiction over saving his life).
In 1864, the American War of Northern Aggression was at its peak and high-ranking Union government officials were looking for ways to take their minds off of the conflict. Congressmen, Cabinet Members, Agency Heads, and other leaders took time to cool off and enjoy a few hours of leisure in the newly-built Congressional Pool just outside of the Washington Monument. Sometimes President Abraham Lincoln would join them. The conventions of the day, however, required that swimmers go into the water fully clothed. This made swimming quite difficult.
By 1865, many swimmers had been through near-death experiences in the pool, weighed down by their soaked clothes as they tried to wade in the deep end. In an emergency session of Congress, called the night that the South surrendered to the North, the Congress addressed the pressing issue by creating the U.S. Life Saving Service. Officers of the service were to be known as "Lifeguards." The Lifeguards were given the sole mission of keeping swimmers in the pool alive. The Service was created not a day too soon, for the very next morning, Abraham Lincoln was taking a dip when his top hat filled with water, pulling him head-first straight to the bottom of the pool. One of the Lifeguards dove in and brought Lincoln to the surface, unharmed. He then, as a personal favor, drove Lincoln to the Ford Theater, where Lincoln was shot in the head by John Wilkes Boothe.
In retrospect, Congress quickly realized that Lincoln would have been better served if the Lifeguard had been equipped with a gun in addition to just a life jacket. At yet another emergency meeting of Congress, the mission of the Lifeguards was quickly expanded to include not only pool service, but also bodyguard services for POTUS. By the early 1900's, the Lifeguards had ceased providing pool services, since the presidents never went swimming, believing it to be bad luck since Lincoln had been swimming on the day of his death. On those rare occasions that POTUS must go near the water, Aquaman is called in and placed on standby.
At any given time, the U.S. Life Saving Service employs some 150 lifeguards. They are responsible for the health and safety of not only the current president, his family, and pets, but also all living past presidents and their families (pets are left to the jurisdiction of Underdog). Although their exact training and skills remain classified, they have been seen in action diving at 90-degree angles, slowing time in order to block bullets, and running backwards at speeds approaching 30 mph. It is widely rumored that the scenes involving Agent Smith and his minions in the movie The Matrix are based on undocumented exploits of U.S. Lifeguards. Still, none of this explains how it was that an assassin was able to kill President John F. Kennedy in 1963, or how an assassin was able to shoot President Ronald Reagan in the 1980's.
Lifeguards must be willing to risk their lives for POTUS and thus must be vetted by a rigorous selection process. First, each candidate is asked, point blank, "Would you take a bullet for the president?" If the candidate blinks or says anything but, "Sir, Yes, Sir!!!," he is disqualified. Candidates must then survive 117 weeks of rigorous mental and physical training at an undisclosed location in the backwoods of West Virginia. The precise nature and details of the training are classified. However, upon graduation, it is known that all Lifeguards are allotted a black suit, white shirt, black tie, sunglasses, earpiece, and handgun. They are also given an honorary pair of swimming trunks, which tradition demands they never wear.
Lifeguards are responsible for the health and safety of POTUS and his family, as discussed above. This means Lifeguards must shadow POTUS at all times. This is awkward when POTUS is relieving himself in the restroom or having carnal relations with his wife, but it must be done. Lifeguards who are found to become aroused in either situation are promptly fired. Also, Lifeguards must truly be willing to take a bullet for POTUS. They must be constantly vigilant for assassins and are specially trained to be on the lookout for people in turbans who approach POTUS.
After 20 years of service, all Lifeguards are forced into retirement. They are ushered to a special facility known as "the Pasture," also at an undisclosed location in the backwoods of West Virginia, where they swap stories about the time they almost took a bullet for POTUS until they die of old age or disease.