07/12/2008 at 11:35 AM EDT
Jaime Pressly is typically in the gym three or four days a week, but her
isn't lifting weights, it's chasing her 13-month-old boy around the house.
"That keeps you in shape," she told PEOPLE at the opening in the Christian Audigier club in Las Vegas. "It's a lot of running around."
The My Name is Earl
star said Dezi James
, her son, is a "really intelligent kid, which is amazing and great, but at the same time it makes you run around like a chicken with your head cut off because he's all over place and he's very determined."
As for Pressly and fiancé Eric Cubiche
, they're just determined to raise their child and not worrying about finally saying "I do".
"We actually got engaged for the baby's sake," she said. "We're really happy
with the way things are and just really focused on our child and our careers
and not really focused on when the date is."