"We kind of talked a bit about the building and how Scott Fitness runs, that kind of thing," Senter says. When it was time for Obama to arrive, Senter held the front door open.

"Down the road come motorcycle cops and unmarked cars and SUVs," Senter says. "I saw him [Obama] when he pulled in the parking lot." She says he wore typical workout pants, a loose long-sleeved T-shirt and headphones.

Obama took a little walk around the gym. Senter says he mentioned that it was "different," but he liked it — the place is decorated with vintage furniture and ’70s portraits and lit with dozens of hanging lampshades, making it feel like the hybrid of a gym and 1970s-sitcom set.

"He was two days away from one of the biggest speeches of his life, so he was focused on getting his workout done and probably hundreds of other things at the same time," Senter says, referring to Obama's Democratic National Convention speech the following Thursday. "The one machine I remember — he used a leg-press machine. He didn’t do a cardio workout. It was all a weightlifting exercise routine. I don’t know how many Secret Service guys were there. If it was me, I’d think it was nice. He had the run of building. It was a slow time during the day."

The Secret Service guys watched the clock. After 45 minutes, Obama indicated that he was finished with his workout. "He shook my hand, said 'Thank you,' and they were gone from the lot and out of my sight in about 60 seconds," Senter says. "I thought that was really cool. I'd never seen anything like that. It was almost unreal."

Later in the day, Obama would stop at the troubled American Airlines facility to address workers facing layoffs.

Senter says she votes "purple," not red or blue, and she hasn't decided who she's voting for yet. But as soon as Obama left the gym, she called her parents and all her friends to tell them about meeting the potential next president of the United States.

"For me, I’m a girl from the suburbs," Senter says. "Presidents and presidential candidates are people you see on TV, not people who walk into where you work and chat with you a little bit."