(CNN) "I'm a grandmother," might as well be Laura Landerman-Garber's catch-phrase. It's something she repeats over and over as she tells the story of how she expanded a small family tradition into a full-blown nonprofit which will send 100,000 cards to US troops this holiday season.

But she's not just a grandma. She's a full-time clinical psychologist living in Hollis, New Hampshire, who -- in her spare time -- runs her nonprofit, Holiday Cards for Our Military Challenge, which she calls a "passion project."

This year, Holiday Cards for Our Military Challenge will send out over 100,000 cards to all five branches of the US military stationed all over the world, she told CNN.

Right now, all the cards are piling up in her basement and have formed an impenetrable wall in her garage, she says.

"The thought of someone being away at a time when in our culture, in American culture particularly, the holidays are all about gathering together... for me, I wanted to be able to reach out and just maybe give a little bit of a bridge so that person who is far away feels a little tiny bit closer to home," Landerman-Garber told CNN.

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