Songfacts®:

• Portland, Oregon-based indie outfit A Weather are fronted by Aaron Gerber and Sarah Winchester. Other band members include Zach Boyle, Aaron Krenkel and Louis Thomas. This is a track from their second album, Everyday Balloons.
• Gerber told the story of the song to AntiMusic: "This song, like a few others on Everyday Balloons, has its genesis in 2007 before we'd even started recording our first record, Cove. I remember coming home from the music store where I used to teach lessons, driving North on I-5 in the beat up Honda CRX I was using at the time. This was when the initial verse melody came into my head. It's rare for me to create lyrics and melody simultaneously, but in this case the first two lines were linked from the beginning: 'No matter when I wake up the day always is the same length…' By the time I was almost home I'd also formed the melody for the pre-chorus (the section when the drums and rest of the band kick in). I recorded those two scraps on Garageband when I got back to my house. I also wrote the song 'Small Potatoes' (from Cove) that same night, and for a little while I was actually trying to combine the two since they both had a similar tempo and an upbeat feel, but I came to realize the two songs were better left independent of each other. Maybe a month later, our guitar player Aaron K. and I spent an afternoon trying to flesh out 'Third of Life' but it didn't feel completed so I shelved it. By that time I'd had the title, which I culled from Counting Sheep, a great non-fiction book about sleep by Paul Martin. 'Third of Life' refers to the average amount of time a person spends asleep.I tend to hold unfinished songs in my head for a long time, always aware that they are there and thinking about how to bring them to completion. In late 2008 I began work on the song again, finally coming up with the chorus melody ('If I'm going to make it across I only want to swim once…').
  Originally I first wrote the harmony that Sarah sings on this section and considered that to be the main theme. The more swooping melody that I sing was actually an afterthought, a counterpoint to the first melody. As might be apparent from listening, the long outro section came from a separate song idea I'd had for a while but hadn't found a home for. It seemed to make a good dynamic ending for the first half of the song so we stuck it on there."
• Gerber explained the song's lyrics in the same interview: "Lyrically the song went through a few versions and I continued revising until right before recording. I discarded most of what I'd written back in 2007 except for the first verse I mentioned above, which had become - for better or worse - an intrinsic part of the song's identity. The lyrics are mostly concerned with the question of when one's life becomes worth something, becomes a completed idea, and if our accomplishments are what define a life and prepare us for death. Also, I was thinking a bit about how as a child you assume that someday you'll know how everything works and how the process of living your life proves the impossibility of this. It's about coming to terms with the anxiety of not knowing."