Timothy Spayd, 53, a former active-duty Army sergeant, was diagnosed with ALS, commonly know as Lou Gehrig’s disease, two years ago. He responded by working out at Ranger School. (Dan Lamothe/ The Washington Post)

EGLIN AIR FORCE BASE, Fla. — As Ranger School students prepared to cross the Yellow River here Tuesday, one of the first soldiers through the water was Timothy Spayd. At nearly 54 years old, he was twice the age of some of the other Ranger instructors, but still waded in chest-deep to help students cross.

Spayd is no typical instructor. A former active-duty sergeant, he was adopted two years ago by soldiers of the 6th Ranger Training Battalion, the unit that runs the third phase of Ranger School in the Florida Panhandle’s swamps. They did so after Spayd was diagnosed with amyotrophic lateral sclerosis, better known as ALS or Lou Gehrig’s Disease. He didn’t want to give up, and needed something to keep him moving.

“Rangers is definitely a brotherhood that I’ve tapped back into, and they’ve given me a sense of purpose,” Spayd said. “I was literally sitting home dying. I was going downhill fast. I think mental toughness is a big deal. It’s a big issue in life.”

[Inside the swamp phase of Ranger School as women attend for the first time]

Spayd, of Milton, Fla., said he first began wondering about his health several years ago. He lost 26 pounds in about six weeks, and had horrendous pain in his back and spine. He and his wife, Karen, spent years trying to figure out what was wrong, visiting hospitals in three states before a Department of Veterans Affairs doctor in Texas told him the bad news, he said.

The disease’s profile was elevated last year by the popular Ice Bucket Challenge fundraiser, and remains a grueling ailment. A progressive neurodegenerative disease, it attacks nerve cells in the brain and spinal cord, affecting voluntary muscle action. Eventually, it can leave people unable to speak or walk. About 20,000 Americans are affected with it at any one time — and for unknown reasons, military veterans are twice as likely to get it, according to the ALS Association.

Timothy Spayd, center with backpack, is an Army Ranger veteran who began assisting the Ranger School in 2013, after he was disagnosed with ALS. (Photo by Dan Lamothe/ The Washington Post)

The Washington Post met the slender, silver-haired Spayd while visiting Eglin Air Force Base on assignment as part of continuing coverage about women attending Ranger School for the first time. He speaks with a clear voice, but said he already struggles with some symptoms. He is prone to fasiculations, a kind of involuntary contraction, in his legs when he sleeps, and he once broke two ribs after falling after feeling weak, he said. After a day at Ranger School, he needs several days of rest.

The activity has been good for him, though, he said. A 1980 Ranger School graduate, he first walked with students at Eglin more recently in 2013, and has now been involved in the last 19 classes, spanning nearly two years. He began after a friend and fellow Ranger School graduate reached out on his behalf to see if Ranger School would allow him to assist and visit — a “Make a Wish” sort of request, Spayd said. Then it kept going.

[Two women past Mountain Phase at Ranger School, now one step short of graduation]

“I was selfish at first. It was for me,” he said. “I wanted to kind of physically push myself past what I would have done at home and to try to get back to the Ranger standard with pushups and everything. I was just really trying, and I’m doing really good. I’m blessed.”

Students are unlikely to know Spayd’s story, he and other Ranger School staff said. But Ranger instructors said they know it and admire him.

“He embodies the Ranger spirit,” said one of them, Sgt. 1st Class Joshua Sullivan. “He understands that being a Ranger isn’t just about your military career. It applies to your entire life.”

Spayd said he thinks he already would have been dead without Ranger School and the change in attitude it prompted for him. He used to attend ALS support groups, but stopped because he found it heartbreaking when friends died, he said.

“I’m a soldier, and I’m a warrior and I think that’s just how I’m made,” he said. “I’m just going to be the one who keeps doing what I can. Our soldiers go through a lot, and in civilian life I don’t think they realize what they go through and what they’re doing. I’m just here to support them and encourage them and make better leaders and better soldiers.”