Rob Lowe Jokes About Being 'a Third Wheeler' on Chris Pratt and Katherine Schwarzenegger's Dates (Exclusive)

Rob Lowe is opening up about his friendship with Chris Pratt and Katherine Schwarzenegger!

When ET's Lauren Zima caught up with the actor in Los Angeles on Monday, he joked about feeling like a third wheel during their hangouts.

The conversation all started when Lowe was talking about some of the things he and Pratt bond over. Seeing as the two both love golf, they've become overly competitive about the sport in recent months.

"Pratt's getting really good. I think we're a really good battle," explained Lowe, who shares two kids -- Matthew, 26, and John, 24 -- with wife Sheryl Berkoff. "We're so evenly matched that there's not a lot of trash talk ... [unless] my sons are involved. I've raised two internet trolls. I don't know how this has happened to me. I thought I was a really doting, loving father."

Schwarzenegger has joined Pratt on some of those golfing adventures, so naturally, we had to ask Lowe if he ever feels left out when hanging out with the adorable couple.

"I'm always third-wheeling with everyone. I'm a professional third wheeler," he joked. "It's just my lot in life. But no, I don't think Katherine's golf game is up to snuff, so we don't need to worry about that. It's still a guy's escape still."

See below for just a few examples of some of the golf course snaps Pratt and Lowe have documented via Instagram:

Later in the interview, Lowe, who is a spokesperson for Atkins, also opened up about how he's looking fine and fit at 55 years old.

"Honestly, it's a lot of years, I think, of making very good choices," he shared. "First of all, I've been sober for 28 years. That helps. I've been living the Atkins lifestyle since my mid-30s, which is low carbs, higher protein, no sugar, and I'm a workout maniac. I mean, you don't want to talk to me in the morning before I work out or have my coffee. I gotta get my adrenaline, my caffeine."

And even though he loves a good golf game, Lowe doesn't consider the sport "a workout."

"Look, it's a good workout for your mind and your concentration unless you're carrying your bag and walking then God bless you," he said. "That's a bridge too far even for me. I'd rather be on my Peloton for 10 hours than carrying a golf bag around."

Hear more from Lowe's sit-down interview with ET in the video below.

RELATED CONTENT:

Rob Lowe Reflects on How 'St. Elmo's Fire' Cast 'All Really Cared About Each Other' (Exclusive)

Shirtless Chris Pratt Has Beach Day With Wife Katherine Schwarzenegger & His 'Parks and Rec' Co-Star Rob Lowe

'9-1-1' Spinoff Starring Rob Lowe, '9-1-1: Lone Star,' Coming to Fox

Related Articles:

• Hollywood Bikini Bods Over 40

• Biggest Celebrity Breakups of 2019

• Celebrities in Their Underwear