08/17/2013 AT 09:20 AM EDT
remembers the exact moment she decided to turn her health around.
"It was about two years ago, before I got married," the actress and View
co-host says. "I was 197 pounds, sitting on my couch, eating pizza and watching infomercials. I am an infomercial whore – I'll watch any of them! But anyway, this infomercial for Zumba showed up and I couldn't get to my credit card fast enough! I knew it was time."
One of her reasons to get in shape: to boost her energy levels.
"I have a very energetic son," Shepherd, 46, says of Jeffrey, now 8
. "And I would take him to the park and sit on the bench while he played. And I was the mom who would be yelling at him from the benches because I was just too tired to move."
Sure, that sounds good. But what was the real
reason she lost the weight?
"You know I wanted to look good for my wedding," she says with a laugh. "I have a closetful of clothes of all different sizes. And I have some that I call my 'Oprah clothes.' Remember when she came out onstage dragging a wagon-full of fat? I have a fantasy of doing the same thing!"
Shepherd changed her diet – no more pizza and infomercial binges – and started taking Zumba classes three times a week.
"I figured, it's just dancing. I've been on Dancing with The Stars!
But after a few minutes, I thought my heart was going to give out."
She kept at it. "I was 197 pounds, and now I weigh 151," she says. "But besides that, I notice the loss of inches. I can wear my Oprah Clothes! They fit!"
She was so impressed with her new favorite exercise that she was the keynote speaker at the annual Zumba convention in Orlando on Thursday.
Now 46 lbs. slimmer, Shepherd is looking forward to the new season of The View
, starting next month. Gone are
Joy Behar and Elisabeth Hasselbeck
, replaced by Jenny McCarthy
"I will miss Joy and Elisabeth," she says, "but that's how things work on the show. Whenever you get used to things, we change it up!"