Long before he served as the fifth president, a young James Monroe fought in the Revolutionary War as an officer in the Continental Army. On Christmas Day 1776, he joined in the famous crossing of the icy Delaware River as part of General George Washington’s surprise attack on a garrison of 1,400 Hessians stationed in Trenton, New Jersey. Lieutenant Monroe was one of the first Americans to make landfall. When the fighting began, he helped lead an assault on a pair of cannons the Hessians were scrambling to aim at the advancing patriots. Monroe was shot through the shoulder by a musket ball during the skirmish, but he and his men continued fighting and held off the enemy until reinforcements arrived and put the Hessians to a rout. Monroe’s wound was grave—the bullet had severed an artery—and he nearly bled to death before being treated by a volunteer physician. Artist Emanuel Leutze would later depict the future president holding the American flag in his famous painting “Washington Crossing the Delaware.”

Born March 15, 1767, the 7th president was 69 years and 354 days when he completed his second term in March 1837. Though “Old Hickory” had a reputation for being a rugged ex-soldier and outdoorsman, by the time he reached the White House, he already had spent years coping with a variety of ailments.

According to biographer H.W. Brands, samples of his hair reveal that he had lead poisoning from old bullet wounds. Jackson also struggled with chronic diarrhea from diseases he’d contracted while fighting the Indians in the 1810s. His habits of smoking and chewing tobacco didn’t help his health either, and according to biographer Sean Wilentz, Jackson became so sick at times during his two terms that it appeared he might not survive.

Jackson did make it to the end of his term but when returned to the Hermitage, his plantation in Tennessee, the white-haired ex-president was physically spent and suffered from blinding headaches, insomnia, severe pains in his side and a chronic cough.

Zachary Taylor won the presidency after leading U.S. troops in the Mexican-American War, but it was during the War of 1812 that he first won fame as a soldier. In September 1812, Captain Taylor was commanding a 55-man garrison at Indiana’s Fort Harrison when it was attacked by some 450 Native Americans allied with the British. The natives set the fort’s blockhouses on fire, and the blaze quickly spread after it ignited the whiskey supply. Taylor later wrote that his citadel descended into chaos amidst, “the raging of the fire—the yelling and howling of several hundred Indians—and the cries of nine women and children.” As the natives poured against Fort Harrison’s outer walls, Taylor mounted a frantic defense. After ordering the majority of his forces to return fire with muskets, he instructed a few others to tear shingles off the roof and use well water to snuff out the blaze. Taylor and his men then built breastworks to plug the burned out gap in their wall. The makeshift defenses managed to hold off the attack until daybreak, and Taylor and his beleaguered garrison later survived a 10-day siege before being relieved by U.S. reinforcements.

On September 14, 1862, the man who would become the 19th president was serving as a Union lieutenant colonel during heavy fighting at the Battle of South Mountain. When Rutherford B. Hayes led his men on a frontal assault against Confederate forces, he was suddenly stuck by a musket ball that shattered the humerus of his left arm. Hayes continued to lead for a few moments before collapsing. While he writhed in agony, his company momentarily fell back, leaving the wounded Hayes stranded in the no man’s land between the two armies. As he lay bleeding on the field, Hayes spoke with a wounded Confederate soldier, and even gave the man messages to deliver to his wife and friends in the event he did not survive. After the firing died down, one of Hayes’ soldiers dragged him from the field and, as he later wrote, “laid me down behind a big log and gave me a canteen of water, which tasted so good.” Hayes almost lost his arm to the musket ball, but it wasn’t the only time the future president was wounded during the Civil War. Before ending the conflict as a major general, Hayes would suffer four separate injuries and have four horses shot out from under him.

Theodore Roosevelt on William McKinley : 'McKinley had no more backbone than a chocolate eclair.'

If it wasn’t obvious, Roosevelt perceived McKinley as a flip-flopper. Awkwardly, Roosevelt became that McKinley’s vice president two years later. And just a few months later, Roosevelt succeeded to the presidency after the man he’d once compared to a French dessert was assassinated.

Teddy’s experience as president didn’t stop him from trashing other ones, either. Using terms that are essentially meaningless today, he called President Woodrow Wilson “a Byzantine logothete backed by flubdubs and mollycoddles.”

The image most people had of John F. Kennedy was one of youth and vitality. And, that was on purpose. JFK in fact lived in near-constant pain, but his poor health was kept a closely guarded secret for fear of damaging his political career. He had allergies, stomach troubles and suffered from chronic back pain, which was aggravated by his World War II service and required numerous surgeries. The back injury allegedly happened in 1937 while he was a student at Harvard, and it initially disqualified him from military service (his father later used his connections to get JFK into the Naval Reserve).

He’d been ill before the injury, too. As a child he suffered from gastrointestinal issues, which were later diagnosed as Addison’s disease, an endocrine disorder. In a strange twist of fate, one of the symptoms of Addison’s—as well as a symptom of the steroids used to treat it—is hyperpigmentation, which may be responsible for JFK’s perpetual “tan,” something viewers of his televised debate with Richard Nixon definitely noted.

Born June 12, 1924, the 41st president had reached 68 years and 222 days in age when he left office in January 1993. After a long career in government that included a stint as Central Intelligence Agency director and eight years as vice president, Bush had a lot of mileage on his tires the time he reached the Oval Office. But a lifetime of exercise had kept the former Yale University baseball star remarkably fit for a man in his sixties.

Bush was a regular runner who frequently invited reporters along on his runs, former White House correspondent Kevin Merida later recalled in a piece for sports website The Undefeated. Bush did have some stumbles that some interpreted as signs of being tired and out of touch, including a moment in which he checked his watch during a 1992 debate and then had difficulty answering an audience member’s question about how the recession had affected him.

Though he lost the election, historians have come to appreciate his achievements as president, including his handling of the end of the Cold War.