11/25/2012 at 11:00 AM EST
burned some calories on Thanksgiving with a SoulCycle spinning class in New York's Union Square neighborhood.
"She was in the middle front row in cropped yoga pants, a pink tank top and a black sports bra," an onlooker tells PEOPLE.
Although she was "on her iPhone until the class started," once things got underway, she was "really bouncy and dancing to the music."
"She had a big smile on her face," the source adds.
– Shakthi Jothianandan