"Glen's legacy is that he wanted to change the world not just with music, but with the disease that took his life," Keach tells PEOPLE

By Nicole Sands and Karen Mizoguchi
August 08, 2017 07:50 PM

The death of country legend Glen Campbell has left many of his famous friends in mourning, including longtime pal and producer James Keach, who produced and directed the 2014 documentary, Glen Campbell: I’ll Be Me.

“Besides being one of the greatest guitar players that ever lived and recording some of America’s standards, I think Glen’s legacy is that he wanted to change the world not just with music, but with the disease that took his life,” Keach, 69, tells PEOPLE exclusively.

Glen Campbell: I’ll Be Me chronicled the late singer’s Goodbye Tour as well as the ongoing medical treatment following Campbell’s Alzheimer’s diagnosis in 2011. Keach, who also produced the 2005 Oscar-winning film Walk the Line, teamed up with Campbell and his family to explore the devastating effects of the disease that ultimately took the “Rhinestone Cowboy” singer’s life.

“When he asked us to make the film, it was an incredible act of courage to let people see it up close and personal like they’d never seen it before,” Keach shares. “The way he carried himself when we did 171 shows while filming was extraordinary. This was a guy who literally was told to hang up his guitar and go home — and instead, he strapped it on and went out on stage.”

Adding, “You can’t deny the guy’s genius. He was one of the greatest guitar players that ever lived, but he was also the funniest, kindest, sweetest people I’ve ever known.”

Credit: David Livingston/Getty

Campbell died Tuesday in Nashville at the age of 81, his family confirmed in a statement posted on his website.

Living full-time at a Nashville memory-care facility located minutes from the Campbell’s home, Glen was cared for by a family friend and personal sitter named Brody, along with his main caregiver and wife, Kim, who visited him daily.

“I saw Glen a few months ago. He wasn’t doing well – still sweet as he could be!” Keach recalls of the last time he saw Campbell at the facility.

“When he first went into assisted living, we’d always bring a little guitar and we came in there – and everybody was nervous of how he’d react,” he remembers. “He picked up the guitar and all these people were sitting around and he says, ‘Would you like me to play a couple of songs?’ And he played a couple of tunes, and then he looked at everybody and said, ‘Thank y’all for coming’ and then sat down on the sofa and went to sleep. He was always entertaining and always willing to sing a song for anybody. He was kind to everybody on and off stage. He was one of the funniest people I ever knew.”

The 54th Annual GRAMMY Awards - Show
Credit: John Shearer/WireImage

And while many fans and friends in the music industry saw Campbell as a country legend, Keach also saw him as a devoted father and family man.

“There’s nothing that Glen loved more than to play music with his children and to be around them. Glen was a lot of things in his life, but he was one of those guys who was totally loyal to his wife and his family,” Keach says. “He was as proud a father as you ever saw. He just loved watching his kids play music, and to play music with them – that kept him alive I think in the last years.”

Campbell’s family said in a statement that in lieu of flowers, donations can be made to the Glen Campbell Memorial Fund at BrightFocus Foundation through the CareLiving.org donation page.