Dan Lamothe covers the Pentagon and U.S. military for The Washington Post. He previously was a senior writer with Marine Corps Times.

William Kyle Carpenter knows the pain will come.

Nine years after throwing himself on a Taliban hand grenade in Afghanistan to protect a fellow Marine from injury, Carpenter is a blur of motion. At 30, he is still the youngest current recipient of the Medal of Honor, the nation’s top award for valor in combat, five years after receiving it in a White House ceremony.

He has run marathons, sky-dived and recently launched a nationwide tour to promote his new book, “You Are Worth It: Building a Life Worth Fighting For” — all after nearly dying three times and undergoing more than 40 surgeries to reconstruct his face, right arm and other body parts torn apart by the explosion. He’s pain-free now, he said, but he realizes that as he gets older, the catastrophic nature of his injuries is likely to cause other problems.

But that’s for another day.

On a recent Friday, Carpenter — who goes by his middle name — was sitting in a dark suit and tie on a blue easy chair in front of 300 people at the National Museum of the Marine Corps near Quantico, Va.

He spoke casually about his injuries, saying that doctors put “Humpty Dumpty back together again.” But he also shared struggles he has faced since receiving the Medal of Honor in 2014, including discovering that some people weren’t sensitive to his personal limits and would add surprise events to his travel schedule without asking him. He was briefly hospitalized a few months after receiving the award in a state of exhaustion, he said.

“My mind-set was that I’m going to say yes to as much as possible, therefore disappointing as few people as possible,” he said. “Now I realize now I had no time to feel. I had no time to think, self-reflect — anything.”

There’s a lot of reflection like that from Carpenter in “You Are Worth It.” While it might look on the surface like a self-help book (chapter titles include “Call Your Mom,” “Don’t Hide Your Scars” and “Say Thank You”), it’s a memoir of gritty recovery and a thank-you letter to the many people who kept him alive and focused on healing.

In some of the most striking scenes, the generally upbeat Carpenter describes suffering through nightmares and hallucinations while on pain medication and breaking down in tears in front of his mother, Robin. He was overwhelmed that his injuries would not allow him to eat a bowl of cereal.

“Through sobs, I managed to choke out one devastating question: ‘Look at me. Who is ever going to love me again?’ ” Carpenter recalled.

It’s a striking admission for a wounded veteran who has been admired for his pluck and grace in the public eye and celebrated as a modern medical miracle. Carpenter has drawn more than 436,000 followers on Instagram and 50,000 on Twitter while eschewing politics in favor of encouraging kindness and gratitude. (Handle: @chicksdigscars.)

For me, as a journalist covering the military, Carpenter’s tale has long resonated.

I became aware of him in 2011, after he accepted an invitation to appear at the South Carolina General Assembly a few months after the explosion. Lawmakers had decided to recognize Carpenter, who spent his last years of high school in South Carolina, for absorbing “the full blast from an enemy hand grenade in seeking to save a fellow Marine,” as they put it in a resolution.

The images of Carpenter, still badly scarred and wearing a prosthetic eye while in his dress uniform, circulated widely online. But few knew his story or how the Marine Corps might decorate him for his valor. If his actions were as compelling as described, I reasoned, certainly he could merit the nation’s highest award for valor in combat.

While working for the Marine Corps Times, I called his parents’ house in South Carolina one night. To my surprise, Carpenter himself picked up. He had more treatment left at Walter Reed National Military Medical Center in Maryland, and he said he’d be glad to tell me his story there if it gave him a chance to highlight the sacrifices that his infantry unit — 2nd Battalion, 9th Marines — had made in Afghanistan.

The Marine Corps probably could have scuttled the interview, but with Carpenter in favor of it, we proceeded. I gently warned him that I’d need to investigate what happened and speak to as many people who knew him as possible. He didn’t hesitate. Instead, he offered phone numbers as a starting point for me to talk to others who were there when he was hit.

The story was published in January 2012. Carpenter has checked in occasionally since and recalled when we met again recently that when he sat down with me to tell his story for the first time, “it wasn’t clear what was going to happen” in the Marine Corps’ investigation of his actions.

In front of the crowd at the museum, Carpenter said he considered writing a book for some time but did not know where to begin. Then it hit him, he said: Everywhere he spoke, people sought him out to tell their own traumatic stories, even if they had nothing to do with the military. What if his book could speak to them, whether they had served in the military or not?

“I thought, ‘Of course!’ ” he said. “Everyone can relate to struggle.”

One on one, he said that with two years of work on the book now complete, he’s still trying to figure out what to do with his future. He called it a “mystery.” For now, he’s not sure whether his message of overcoming adversity can break through in a country facing deep divisions, but he wants to try.

“Now, that’s truly the million-dollar question,” he said. “I truly hope so. I truly hope so.”

Carpenter said that “by no means” has he lost hope in the United States, but he thinks “we need a heavy dose of perspective” and to remember that “we are all human beings” and Americans.

“I might be kicking myself after this interview because I could have said something better or more profound,” he said, choosing his words carefully. “But I think most importantly, we need to realize that not everyone is privileged or born into a good life, stable homes or a home, period.”

Raised a Baptist, Carpenter said he never lost faith in God during his three years in the hospital. But the ordeal did make him wonder why he survived, and he thinks that’s healthy.

“You know, I’m still working through it, and I still believe,” he said. “Obviously, the line of miracles that got me to where I am is incredible. It’s almost so surreal, to believe that they all fell the way they did.”