Retired Lt. Gen. Mark Hertling is a national security, intelligence and terrorism analyst for CNN. He served for 37 years in the Army, including three years in combat, and retired as commanding general of US Army Europe and the 7th Army. He is the author of "Growing Physician Leaders." The opinions expressed in this commentary are solely his.

For my money, that's the best line ever spoken in any war movie. Playing the role of a dying Capt. Miller in "Saving Private Ryan," Tom Hanks pulls Ryan -- played by Matt Damon -- in close and demands that he live his life in such a way as to pay back the sacrifices and deaths of those who had come to save him.

No matter how many times I see that film, it always affects me the same.

In fact, as I grow older, it seems to influence me more. Instead of seeing Ryan of World War II, I see many other faces and recall many other names of those who I served with and who gave their last breath for something greater than themselves. And I wonder if I'm doing enough to earn it in their eyes.

There's a wooden cigar box on my desk that holds cards with the photographs of 253 soldiers, sailors, airmen, allies and civilians who served and made the ultimate sacrifice under my command in combat. They epitomize America's best, and their pictures represent the kind of people we all should aspire to be.

When I open the box every day, I pick a few of those pictures and pray for their families -- their wives, husbands, children, parents, loved ones. I often wonder what miracles each one of them could have experienced in their lives if they had been one of the ones coming home.

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Just this week I picked up the photo of Command Sgt. Maj. Eric Cooke, who was killed just a few hundred yards away from me in 2003 on Christmas Eve. His vehicle was struck with an improvised explosive device (IED). Right under his card was the one of Pvt. Jonathan Falaniko, a good-looking kid from Samoa who was the son of one of our other command sergeant majors. Pvt. Falaniko was killed in action just a few weeks after arriving in our unit while he was patrolling down a road. He was 19, and his father, Command Sgt. Maj. Iuniasolua Falaniko, had to do something no father should ever have to do: escort his son's body back from Iraq to his mother, and then on to Arlington National Cemetery.

As I went through the photos this week, I saw the ones of Staff Sgt. Du Tran , the son of a Vietnamese immigrant, and Mexican immigrant Pvt. Rey Cuervo . Tran's wife -- the daughter of an immigrant -- was back in Germany with their three children at a US Army base that memorialized her young husband. Our division named a forward operating base after Cuervo. Immigrants, since the early history of our Army, have been part of our ranks, looking to serve their new country, earn citizenship and be accepted in society.

Although there are many photos of fallen soldiers that I go through daily, the one that I picked today is the one that inspired me to write this piece. It's the picture of 1st Lt. Thomas Brown in his desert floppy hat and sunglasses. He's smiling and giving a one-handed thumbs up. Brown was a charismatic infantryman from Connecticut, killed on September 23, 2008, and survived by his mother. As I look at his picture -- one that will allow him to remain forever young -- with his big grin and devil-may-care visage, I wonder what could have been.

These are all our nation's very best. When we send them off to war, we inherently know some will never come home alive. During those heart wrenching times, we are left to contemplate our personal loss. Still, we must also reflect on all the goodness that might have been.

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Each person who raises their hand and vows to protect and defend our Constitution makes a commitment to give their all. And some of them do just that. When they don't come home, the daily decisions we make and the daily actions we take in serving our nation and each other become the measure of our commitment to them. We honor their sacrifice by making a commitment to serve our nation and each other. We have an obligation to honor their memories by the way we lead our lives, the way we speak, the way we act, and the way we carry on each day.

We have to earn it.