Glenn Frey's death at the age of 67 stunned his fans, but in a new interview, his longtime friend and fellow rock legend Bob Seger reveals that Frey's health had been much worse than most people knew.

Frey died on Monday (Jan. 18) in a hospital in New York City, succumbing to complications from rheumatoid arthritis, acute ulcerative colitis and pneumonia. He had undergone stomach surgery in November, which caused the Eagles to push back their Kennedy Center Honors, and according to Seger, he never left the hospital.

The pair had been friends since their early days together in the Detroit music scene, and a young Frey even played guitar and sang backing vocals on Seger's "Ramblin' Gamblin' Man," long before he found fame in the Eagles. Seger tells the Detroit Free Press that Frey was always one of his greatest cheerleaders and friends over the years, and he was concerned when Don Henley contacted him in November to tell him Frey was hospitalized and in poor health.

“He was in a coma, and he’d come out, but then he couldn’t breathe. They’d put him back into the coma,” Seger recalls. “They were trying like hell to keep him alive … [Eagles manager] Irving [Azoff] pulled every ace out of the hole — he had the eight best specialists working on Glenn.”

Those efforts proved to be in vain. “About a month ago, they had to throw up their hands.”

Frey had a long history of stomach problems, which he attributed to his period of alcohol and drug use in the 1970s, according to the Washington Post. Beginning in the '80s, he settled into a happy home life as a husband and father, and led a healthy lifestyle that included an extensive workout regimen. Seger says there was much more to his friend than the public ever saw. In fact, the last time he and Frey saw each other at an Eagles gig in July, Frey had to fly in last-minute after attending one of his kids' graduation.

“He loved his family. He loved those kids. He was devoted to them," Seger states. "He was so much more than people knew he was … He would never fail to start with telling me how grateful he was that audiences were still there. He loved the band. He loved the fact he could keep doing this. And he kept doing this until six months before he died."

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