The Hills are alive with the sound of Speidi!

Former MTV reality stars Heidi Montag, 25, and Spencer Pratt, 25, spent Thursday afternoon hitting the slopes in Mammoth, Calif. In addition to skiing, the couple went sledding and snowmobiling -- all while packing on the PDA, natch.

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"It was so much fun," Montag tells Us Weekly. "There is no better way to get in the Christmas spirit than being out in the snow and skiing."

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Montag, who grew up in Crested Butte, Colorado, says the afternoon adventure was a "really nice break" from school. (Pratt is currently pursuing a political science degree at the University of Southern California.)

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"It helped get us in the Christmas mode. It was the best trip ever," Montag tells Us. "This has been the best year of my life, and I'm very excited to see what 2012 is going to hold."

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