Nearly four years after the release of his last album and three years after "I'm Yours" became a record-setting smash hit, Jason Mraz has returned with "I Won't Give Up," the first glimpse of his fourth studio album. The singer-songwriter unveiled the song and its accompanying lyric video on Monday (Jan. 2).

"I Won't Give Up" is a wistful, astrology-tinged ode to a long-lasting romance, with Mraz singing, "Just like them old stars/I see that you've come so far/To be right where you are." The video showcases a faceless man and woman taking a trip down memory lane by separately sorting through a collection of envelopes, postcards and scraps of notebook paper; in the end, they find their way back to each other, stationery safely nestled in their hearts.

The guitar ballad is in line with how Mraz has described the sound of his still-untitled fourth album, due out in the top half of 2012. Last month, the pop singer told Billboard.com that the new album "has less horns -- it's got more piano and guitar textures. A lot more vocal landscapes… That, to me, has always been my favorite part of making music; the singing and what voices can do and the voices singing in harmony." At the time, Mraz said that the new full-length was "all but one song" away from completion.

Mraz's previous album, 2008's "We Sing. We Dance. We Steal Things," has sold 1.67 million copies since its 2008 release, according to Nielsen SoundScan. The disc was supported by the jaunty single "I'm Yours," which spent a record 76 weeks on the Hot 100, surpassing LeAnn Rimes' "How Do I Live," which spent 69 weeks on the tally in 1997-98.