The first note of this song marked the first time feedback was used on a major release. It was created when John Lennon leaned his electric guitar against an amplifier and Paul McCartney played a note on his bass, creating a strangely appealing feedback loop. The band thought it sounded great, but in this pre-Hendrix era, feedback was considered a technical malfunction and not an artistic enhancement. Fortunately, their producer George Martin was always open to new ideas and agreed to insert it at the beginning of the song. "He'd let us experiment like nutty professors," McCartney said of Martin.
An early Beatles track, "I Feel Fine" lyrically is a simple love song about a guy who is crazy about his girl. It's not Shakespeare, but it's effective:
She's so glad, she's telling all the world
That her baby buys her things, you know
He buys her diamond rings, you know
John Lennon wrote the majority of this song, which borrows from the "Watch Your Step" by the American blues musician Bobby Parker.
In 2008, Parker told the Forgotten Hits newsletter: "I've been in litigation for close to 55 years about some of this material that was stolen from me. They had 'Watch Your Step' on John Lennon's Jukebox and then that went out all over the country on PBS Television and people heard about it. John Lennon said how he had 'borrowed' that guitar part for HIS record, and pretty soon everybody knew about 'Watch Your Step.' I go over to England now and that's all they wanna hear, they don't even care about the new stuff I'm doin'. I'm out there playin' with Buddy Guy and Robert Gray, and they just wanna hear 'Watch Your Step' from John Lennon's Jukebox!"
The refrain is typical of Lennon's songwriting, with the three long notes: "I'm so glad." The sudden explosive refrain in harmonies is similar to Giovanni Gabrieli's grand concerto "In ecclesiis," an early baroque-music-piece.
There is a very faint sound at the end of the song that was rumored to be barking dogs. It's actually just McCartney goofing around.
The Beatles included this in their setlist when they toured the US in August 1965. Prior to their famous Shea Stadium appearance on August 15, they taped a performance of this song and five others for an Ed Sullivan Show episode that aired September 12.
The group made two music videos for this song as part of a one-day shoot where they banged out takes for four others as well. These were not high-concept films: just the band having some fun while lip-synching the tracks. The first "I Feel Fine" video got pretty goofy, with Ringo riding a stationary bike. For the second, the band simply sits down and eats lunch. This later version wasn't released until 2015 when it was included on the 1+ collection.