Jackson recently opened up to ET's Nischelle Turner, and the pair eventually landed on the subject of Cowell's recent back injury and subsequent surgeries.
"I also had spine surgery a year and a half or so ago, so it's funny both he and I are having all these back pains," Jackson reflected. "But he's doing great. He's really doing great."
Cowell was forced to miss the last half of the most recent season of America's Got Talent when he broke his back in several places while riding an electric bicycle near his home in August. He underwent emergency surgery and physical therapy to get back onto his feet.
"I kid him," Jackson said. "I say, 'Look, we're getting a little bit older, we're 36 now, internally, but we ain't 30 no more dawg. We gotta like respect the body, yo!'"
One thing Jackson has done to respect his own body is to get into shape and slim down significantly to improve his health. The iconic artist has lost over 114 pounds on his weight loss journey and said it all came down to changing the reasons he eats, as much as what it is that he consumes.
"I just went through a food divorce and I stopped emotional eating," Jackson said. "I was just trying to get healthy because I developed Type 2 diabetes and I had to. So I'm happy that I did, and I'm happy that it inspires people."
Jackson is also staying in shape by staying busy. He's rejoined the iconic rock group Journey, and the famed bassist says that things are going to be a little different when it comes to future tours -- at least, when it comes to ensemble.
"No more leather, no more pleather. No more with the whole hairdo," Jackson said with a laugh. "I gotta change it up now."
Apart from his work with Journey, Jackson is also serving as the band leader on the latest iteration of Name That Tune on Fox, working with host Jane Krakowski.
"Jane is fantastic, she is amazing and you know, she is a triple threat. She acts, sings and dance and does the whole thing so you know we are like live performers," Jackson marveled. "I did not want to go back on a show like Idol... for me, it will live on as the best music show ever... But I love game shows and I grew up watching Name that Tune as a kid in Louisiana, so I was like, 'Man, this is the greatest opportunity to do a game show.'"
"It was just the perfect storm for me," he added. "And Jane and I hit it off right away because she is fun, funny, we are cracking each other up."
Name That Tune airs Wednesdays at 9 p.m. ET/PT on Fox.