I had to sit down and make sense of my feelings and experiences. I learned a lot from the first record that helped me to develop. I took the good and the bad and considered some of the choices I made and became better because of it." Aguilera considers "Fighter" a "natural" and authentic song, adding that "when you can be honest, you can be free, and when you're free, you do your best work." "Fighter" is a rock song. Sal Cinquemani from Slant Magazine said that "Fighter" is a hybrid of R&B and rock. Meanwhile, a reviewer of Billboard described the song as arena rock-influenced, and AOL Music's Nana-Adwoa Ofori noted the elements of rock and roll. However, Nick Levin from Digital Spy detailed "Fighter" as an arena rock piece. The song was inspired by band Guns N' Roses' song "November Rain" (1992). Written in the key of E minor, "Fighter" has a moderate tempo of 96 beats per minute. Brian Hiatt from Entertainment Weekly and Chuck Taylor for Billboard likened the track's musical style to that of Janet Jackson's "Black Cat". Aguilera's vocals on the track span from the low-note of G3 to the high-note of G5; Taylor labelled Aguilera's vocals "tornado of a vocal." At the beginning of "Fighter", the guitar sound was arranged in the chord progression of Em – G/D – D – C – Em/B – B – Am – C/G – G – B7. Aguilera speaks the lyrics, "After all you put me through, you'd think I'd despise you / But in the end, I wanna thank you, 'cause you made me that much stronger" on the guitar theme by Dave Navarro. Lyrically, Aguilera wants to thank the man who did her wrong rather than insult him, because he helped make her stronger and work harder, thus making her a fighter. At the chorus, she sings, "'Cause it makes me that much stronger/ Makes me work a little bit harder/ Makes me that much wiser/ So thanks for making me a fighter". The chords in the guitar part are E5 – F5 – G5 – A5 – B5 − C5 – B5 – A5 – G5 – F5 – E5. She continues, "Made me learn a little bit faster/ Made my skin a little bit thicker/ Makes me that much smarter/ So thanks for making me a fighter". The lyrics of "Fighter" have