Frontman Michael "Fitz" Fitzpatrick was getting bogged down writing for Fitz and the Tantrums fourth album. He found himself questioning his talent and fighting off insecurities, trying to find a way to keep going. The music for this energetic song has a fun and carefree vibe; it pulled Fitzpatrick out of his funk and hyped him up and gave him the spur to keep going. He sings on the bridge:
Hyped up ready to go, I got my eyes on the prize I'm sick of feeling the lows I wanna roll with the highs
Fitzpatrick explained in a press release that penning this track was the turning point of the record for him, "capturing the moment when optimism, hope and confidence were found after a dark period as an artist trying to write for this album."
The song features vocals on the hook from a kids chorus comprising band members' children and some of their friends.
"123456" recounts how the process of writing a song can literally shift one's mood. Fitz explained to Billboard it pulls you "from self-doubt and insecurity to holding on to a fleeting moment of self-confidence and feelin' yourself!"
Carla Thomas became the first woman to achieve a Top 10 hit on the Hot 100 with a song she wrote herself when "Gee Whiz (Look At His Eyes)" reached the chart's top tier in 1961. Thomas was just 16-years-old when she penned it.