President Trump stood in the White House's grandly decorated East Room on Thursday afternoon and read from a teleprompter as he explained how his administration will launch "a massive advertising campaign" to tell children to never try drugs.

Then the teleprompter halted as the president went off script.

"I learned myself. I had a brother, Fred. Great guy, best-looking guy, best personality — much better than mine," Trump said, as those gathered in the room, many of whom have lost loved ones to the opioid crisis, laughed at the overly confident president's rare jab at himself. "But he had a problem. He had a problem with alcohol. And he would tell me: 'Don't drink. Don't drink.' "

The president rarely talks about his older brother, Fred Trump, an airline pilot who struggled with alcoholism and died in 1981 when he was just 43. The two were separated by eight years and were constantly competing for their father's attention, causing their relationship to be rocky at times. President Trump has said that he looked up to his older brother and that his death was "the saddest part in what I've been through."

"To this day, I've never had a drink," Trump told the crowd. "And I have no longing for it. I have no interest in it. To this day, I've never had a cigarette. . . . He really helped me. I had somebody that guided me. And he had a very, very, very tough life because of alcohol. Believe me — very, very tough, tough life. He was a strong guy, but it was a tough, tough thing that he was going through. But I learned because of Fred. I learned."

In sharing his experience on Thursday afternoon, the usually boastful president briefly revealed a more reflective side of himself, trying to connect with those in the room — and those watching at home across the country — who have lost a loved one because of addiction.

"This lets them know that he is one of them," said New Jersey Gov. Chris Christie (R), who is leading the White House's commission on combating drug addiction and the opioid crisis.

[Confident. Incorrigible. Bully: Little Donny was a lot like candidate Donald Trump]

Fred Trump's death more than 30 years ago seems to have shaped the way the president thinks about substance abuse and addiction. His emphasis on abstinence appears rooted in what has worked for him personally — but it is also rooted in the 1980s, when then-first lady Nancy Reagan urged schoolchildren to "just say no." Scores of researchers since that era have concluded it doesn't work very well, however, and some advocates say the approach often deepens the stigma of addiction and suggests that those with a problem should be able to stop easily.

In addition, as many people in the room Thursday know all too well, opioid addiction usually starts much differently from alcoholism. While there are young people who start experimenting with pills they find in their parents' medicine cabinets, many addicts have said they got hooked when they were legally prescribed a painkiller following surgery or a serious injury. While an alcoholic can continue to legally buy alcohol, opioid addicts usually end up illegally buying prescription drugs or switching to heroin, which is sometimes laced with fentanyl, a powerful painkiller. And while severe alcoholism can eventually lead to death, an opioid overdose can quickly kill — and is killing Americans at a rate of roughly 100 per day.

[How the government can fight the opioid epidemic under a public health emergency]

Trump said that if his administration follows through on its plans for this awareness campaign — along with a handful of other initiatives announced on Thursday, including increasing the number of places where Medicaid recipients can get drug treatment — then "the number of drug users and the addicted will start to tumble downward over a period of years" and "it will be a beautiful thing to see."

He acknowledged that millions of Americans are already addicted, and said that he has "no choice but to help these people that are hooked and are suffering, so they can recover and rebuild their lives with their families."

But he kept coming back to the idea of never starting in the first place — a message that he and first lady Melania Trump have been preaching in recent weeks.

[Trump’s advice to kids: ‘No drugs, no alcohol, no cigarettes.’]

"If we can teach young people not to take drugs — just not to take them," the president started to say, then cutting himself off with another personal experience: "When I see friends of mine that are having difficulty with not having that drink at dinner, where it's literally almost impossible for them to stop, I say to myself, 'I can't even understand it. Why would that be difficult?' But we understand why it is difficult."

He continued, returning to his original thought: "The fact is, if we can teach young people — and people generally — not to start, it's really, really easy not to take them. And I think that's going to end up being our most important thing: really tough, really big, really great advertising so we get to people before they start, so they don't have to go through the problems of what people are going through."