Songfacts®:

• Mac Miller spoke openly about his issues with depression, and many of the songs on Circles are about his struggles. Here, the rapper talks about how he has to deal with his negative thoughts on a daily basis. He urges listeners not to make the same mistake that he has of living inside his head. There is also a note of optimism as The Blue Slide Park rapper sings of the hope of "another open door to come up soon."
• Producer Jon Brion, who was with Miller when he recorded "Once A Day," told Apple Music he bawled his eyes out after listening to the heartbreaking lyrics in the studio.
  
  Brion continued to feel emotionally overwhelmed while the song's recording was taking place. As he added a keyboard or guitar part, the producer would hear the vocal before running out into the hallway and bursting into tears again.
• Brion completed the Circles album following Miller's death in September 2018. The producer recalled to The New York Times how devastated he felt when he first listened back to the song during a flight.
  
  "When I heard 'Once A Day' on that plane, it was like a knife in the heart," he said.
  
  Brion added that Miller was "clearly trying to sort through his demons and was just being very, very honest, not trying to hide any of it."
• Many of the Circles tracks credit Brion or other frequent Miller collaborators as co-writers. This is one of three songs the rapper has sole writing credit on, along with "Circles" and "That's on Me."
• Mac recorded his "Once A Day" demo on his cell phone. The October 31, 2018 Mac Miller: A Celebration of Life concert, features footage of him singing the lyrics and playing the song on the piano.