The song was an unusual collaboration between bassist, Peter Cetera and trombonist, James Pankow. Regarding the song's composition, drummer Danny Seraphine recalled,
"Peter wrote that song [with trombonist/percussionist James Pankow] about his marriage falling apart. He'd gone through a real hard time and was starting to feel stronger again"
Cetera himself recalled, ""I can remember the exact beginnings of that one," says Cetera, who co-wrote the rock song that returned Chicago to the Top 10 of the Hot 100. "We were at the Akron Rubber Bowl in Akron, Ohio, an outdoor gig that was delayed a bit because of rain, and so, we got there our normal hour and a half before the gig, and we're sitting around, and we were told we're gonna hold for at least an hour, and I heard Jimmy [Pankow] in the other room playing the actual beginning of that song, and I said, 'Well, that's nice.' I walked over, and I said, 'What is that?' and he went, 'Oh, I don't know, I'm just messing around.' So, I said, 'Well, God, I like that,' and he goes, 'You do?' and I went, 'Yeah.' I went and got my bass, and we sat there and played around with it, and a few weeks later, after we got off the road, I went to his house, and we wrote 'Feelin' Stronger Every Day.'"
With Pankow noting, "Stronger Every Day' was about a relationship but yet, underlying that relationship it's almost like the band is feeling stronger than ever.”