"It was so easy for me when I did it before," Alley – who lost a whopping 75 lbs. when she was a spokesperson for Jenny Craig from 2004 to 2007 – tells PEOPLE.
Although the Dancing with the Stars alum only intended to lose 30 lbs. this time around, she ended up dropping 50 lbs. and going from a size 12 to 14 to a size 6 to 8.
"There's this certain place I hit where I felt really energetic and agile. I was like, I want to keep going with this!" she says.
To avoid her past yo-yo-dieting downfalls, Alley, 63, wanted to take a different approach. "I thought, how am I going to solve the problem of hitting a goal and having enough fun to keep that going?"
So she bought a new set of wheels – for exercise.
"I got a yellow townie bike and I ride over to friends' houses. I bribe people. I'll say, let's ride to this restaurant and I'll pay for dinner," she tells PEOPLE. "And believe me: If I bike four miles to a restaurant, I don't wreck it with my order!"
At home, Alley fills up on organic fruits and vegetables and her Jenny Craig meals, enjoying favorites like chicken fettuccine for lunch and chocolate brownies for dessert. Along with portion control, she says having a consultant has really helped with her slim new figure.
"I started looking at myself as an athlete. I was a competitive swimmer for a very long time and I remember that I wouldn't have won anything or done well in swimming if I didn't have a coach."
It's part of her overall strategy to do what worked well for her in the past to ensure future success. "I want it to be part of my life this time," she says. "I'm just trying to make it fun."
For more on Kirstie Alley's weight loss, pick up this week's issue of PEOPLE, on newsstands Friday