Before iTunes and Spotify playlists existed, people compiled their favorite songs on mix CDs and cassettes. They were a cheap yet thoughtful gift for birthdays, professing your undying love to your crush, and the like.

Singer-songwriter Andrew McMahon understands the magical powers of a really, really good mixtape. He wrote an entire song -- "The Mixed Tape" from Jack's Mannequin's debut record, Everything in Transit (2005) -- about one. Then he made a real-life mixtape to win over his longtime girlfriend, Kelly Hansch. Today, over a decade later, they're married with a daughter, Cecilia.

"So the mixtape worked, sort of," McMahon joked to MTV News. He currently performs solo under the moniker Andrew McMahon in the Wilderness and is gearing up for a summer tour with Weezer and Panic! At The Disco.

"[Kelly and I] were separated, and I had been keeping this journal. Every time a song came on that made think of her or whatever, I would write that song down," McMahon explained. "The idea was that I would make her this epic mix, you know, because we were gonna get back together, and I knew it." His tracklist included The Beach Boys and, notably, Air's "Kelly Watch The Stars."

"I wrote the song before I actually even made the CD [for Kelly]," McMahon continued. "It was about this idea of making the greatest mixtape ever that sort of says it all -- what it's like to be a broken-up 22-year-old."

With lyrics like "This mix could burn a hole in anyone / But it was you I was thinking of," the tune perfectly captures the turbulence that comes with young love. It's no wonder it became a bit of an anthem for teens sharing their angst and heartbreak on Myspace. One Tree Hill's Peyton Sawyer (Hilarie Burton) loved the song so much, she starred in its 2006 music video.

Breakups inspired most of Everything in Transit, in fact. During McMahon's rough patch with Hansch, he also "broke up" with his first band, Something Corporate -- with whom he penned "Konstantine," a 10-minute, piano-heavy ballad that was practically iconic in the early 2000s pop-punk scene.

After ending Something Corporate, McMahon started Jack's Mannequin, and Everything in Transit was born. That pesky "oh shit, I'm a real adult in the world" stage of life fueled his songwriting.

"I sort of blew up all the major relationships in my life and shaved my head and went and hid in a recording studio and wrote songs about it," McMahon said, calling "Dark Blue" the "finishing of that chapter."

"It was this moment where I realized, OK, I've exercised these demons," McMahon revealed. "That was where this metaphor of [a] flood coming through and taking out the whole of California [came in]. It was just me and this girl left floating in the water, and we sort of ended up doing that, so it worked out."

Judging from this precious photo of McMahon and his daughter, it definitely looks like everything worked out just fine.