"I started reading this book, Yes Day, by Amy Krouse Rosenthal years and years ago to my daughter and she just used to say, 'I dream of a yes day. I dream of a yes day.' So I finally decided to do a yes day," Garner said. "... I set up some rules. [I said], 'We're not going to buy things' -- although we usually buy lottery tickets or something small -- but [I do] something I wouldn't normally do. So, we do it every year and it's always something they can make me do what they want."
This year the 46-year-old actress' kids -- Violet, 12, Seraphina, 9, and Samuel, 6 -- had her swing down a metal slide contraption.
"This year they made me do this," she said referring to an Instagram video of the moment. "I do this thing with them called 'Coach Mom' where if they have too much energy I run them around the backyard. I make them do push-ups, I make them do jumping jacks. I'm like, 'Coach Mom!' So they did 'Coach Kids.' They almost killed me. I mean, I thought I was in good shape, [but] my kids were like 'Go mom!'"
Also this year, her three kids -- who she shares with ex-husband Ben Affleck -- played, ate and stayed up as late as they pleased.
"They had ice cream for breakfast. We had a fort inside. We stayed up late," Garner revealed. "It's the longest day of the year! It's one day a year."
While almost anything is a go on Yes Day, Garner has had to draw the line sometimes.
"The toy store or getting ears pierced or buying a puppy, those are not up for grabs on Yes Day." she said of her previous denials. "Cheetos, which I would normally say no to, on yes day I'll give that a pass."
Though giving kids free reign for even one day a year may seem like an unwise decision, Garner describes the day as "so fun."
"I'm strict. I'm pretty strict. My daughter says I'm Amish. I prefer strict, but it's nice to just have a day," Garner said. "...The other thing is all day I say 'Top priority! Yes! Yes!' I act like I'm going to freak out if I don't make it happen that second. They just love it. It's so fun."
More with Jennifer Garner! She's talking about her "yes day" with her kids, taking questions from our audience here in Times Square, and more! pic.twitter.com/iU97eXtPbf