The 48-year-old bassist admits he had serious doubts about continuing with the group when the guitarist - who has since been replaced by Josh Klinghoffer - finally quit in 2008, but eventually decided to stay after finding a "profound love" for his band, especially lead singer Anthony Kiedis.
He said: "I'd thought that if John did go that I would definitely not want to continue the band without him. But after he left, something kind of shifted In Me and I found a really profound love for the Chili Peppers and particularly for Anthony."
He added to Q magazine: "The trickiest part of getting together with Josh for me was also the best, which is that he's completely different to John.
"There were things that I had come to expect John to do: he's such a phenomenal musician that I was used to playing something and - bam! - John would hit it.
"He and Chad [Smith, drummer] would lock in, and it was undeniably good. Josh is way different. He'd be floating around the outside with this ethereal, textural thing. It was like, 'Whoa! When's he gonna do the thing that we know?' And he didn't. I had to consciously say to myself, 'Dude, relax.' "