In an interview with PEOPLE for their latest cover story, John, a TV writer and actor, got candid about his close relationship with his father, explaining why he credits Rob as a large part of the reason that he's sober after previously struggling with addiction.
"When you consider what he went through in his 20s, his meteoric rise and some turbulence, and being in the public eye for decades... To come out a family man, a really, really good father, a really, really strong husband, and just a fun, kind guy to be around, that's the day-to-day example he sets," John, 26, said of his dad, who also shares son Matthew Lowe, 28, with wife Sheryl Berkoff.
John -- who attended Stanford University -- said his dad was there for him when he entered a hard time in his life during his late teenage years.
"On the most personal level possible, when I was struggling with addiction, he was always there for me," he told PEOPLE. "I credit that with being one, if not the main, reason that I'm sober and living a healthy lifestyle."
Rob, 57, has been open with his own journey with sobriety. The "9-1-1: Lone Star" actor struggled with addiction -- including drug and alcohol abuse -- when he got into the party scene after he finding fame as part of Hollywood's Brat Pack with films such as 1983's "The Outsiders" and 1985's "St. Elmo's Fire." He told PEOPLE that he "became so identified" with his character from "St. Elmo's Fire," Billy Hicks, saying, "the wild, fun, rock and roll, quasi-debauched with the heart of gold [guy]: that's my early twenties in a nutshell."
Rob revealed that he noticed similarities in his son, saying John was "taking 'work-hard, play-hard' to the extreme." The "Parks and Recreation" star -- who committed to sobriety in May 1990 -- added, "I really knew Johnny was a chip off the old block, as his big thing was, 'Dad, I'm getting straight A's at Stanford. How much of a problem could I have?' That [justification] was my thing."
PEOPLE noted that Rob "offered love, steady support and his experience" to John, who said it was "majorly instrumental."
"He never gave up on me," John recalled. "I have a little over three and a half years [of sobriety] now, but when I took my first-year chip, he and I spoke at a [12-step] meeting in front of 200 people. And it was one of the most profound experiences of my life."
Meanwhile, Rob explained what it means to him to go through the experience with his son.
"It's one of the great gifts of my life to have Johnny in our [recovery] club, in our wonderful, f---ed-up, extraordinary club," he told PEOPLE. "To give him his one-year [sobriety] chip, and for him to give me my 30-year chip, it defies articulation."
John's older brother Matthew, a lawyer who lives with John in L.A., said he saw his brother's struggle with addiction and journey to sobriety and, more in particular, how their father impacted him.
"The whole family rallied around [and] having someone who has such experience in the realm of sobriety to lead the charge was so invaluable," Matthew explained.
"He does the same thing in everyday life: [Whether it's] me going off to college, or to law school, he's always the cheerleader," he said of Rob. "He's the first one to do absolutely anything to help you succeed."