"I am the laziest person you can imagine," Faris, 32, told PEOPLE at the LG Rumorous Night bash in L.A. on Tuesday. "I do hike and like to be outdoors, but I hate any competitor sports because I am so bad at them."
And, unlike brides-to-be who work hard to slim down before their weddings, Faris is enjoying putting some weight on – and keeping weight where she's already got it.
"I am fattening it up!" she confessed when asked if she'll be changing her workout routine for the big day. "Now that I have a man, I'm like, 'Oh, I don't have to try anymore! Now I can eat. We love to splurge at home. We love to cook. My fiancé is an incredible eater, and so he's really fun to feed, and it's great to share some wine and watch a movie. He's always like, 'Baby, don't lose that butt!'"
The couple costar in next year's dramedy Young Americans.