Outside, on the street, the temperature is high and spirits are low. But inside it’s the reverse. Why? Because Val Richman has dimmed the lights, started the mirror ball, cranked up the A/C and jumpstarted the Lunch Beat.

The Internet, television, radio and newspapers will tell you that Lunch Beat began two years ago in a public garage in Stockholm, Sweden, as founder Molly Ränge and 14 others danced away their lunch hour. But almost a decade ago, Richman had the same idea.

She called it Twist & Shout. She held it in the evening, and it was two hours long, but the concept of dancing  just for the pleasure of moving was the same.

So when the Lunch Beat concept percolated to this country, Richman was ready. She had the music, the sound system and a ready-made base of Twist & Shout devotees. “Petaluma was the first U.S. city to join the international Lunch Beat movement,” she says.

Forget “Dancing With the Stars” or “So You Think You Can Dance.” As they say, Just Do It.

Don’t know the steps? Don’t have a partner? You can dance with someone or by yourself. You can dance with everyone. All you need to do is stand up and dance.

Like milk, Lunch Beat offers something for everybody and every body, box step to bossa nova, swaying side to side, salsa and samba.

There are “rules,” or as lunchbeat.org phrases it, a “manifesto.”

The first is: If it’s your first lunch at Lunch Beat, you have to dance.

Second rule: If it’s your second, third or fourth time lunching at Lunch Beat, you have to dance.

You’re also forbidden to talk about your job, but here in Petaluma that doesn’t seem likely. The music’s too lively.

Annette Johnson came with a friend. “This was so much fun,” Johnson said. “I’m going to do it again.”

Lunch Beat dancers move to the music of DJ Val Richman.

Her friend, Gloria Robinson, had another reason for coming. “I’m 70, and I had heart surgery in April,” she said. “But I can still move.” She danced the whole hour and laughed her way out the door.

Peter Saunders, who has known Richman a long time, says dancing “is the best exercise. I feel great afterward.”

And Helen Pitt, a reporter for the Sydney Morning Herald, joked that she came “all the way from Australia” for Lunch Beat. “I used to live in Petaluma,” she explained. “I knew Val was the DJ queen, and Lunch Beat is a worldwide movement. It’s lovely to think of people going out into the bright sunshine all energized.”

After the music ended and the lights came up, Richman was able to sit down (she danced as well) and talk about dancing just for the fun of it.

“I play a wide variety of music,” she says, “as long as it has a beat. I’ve been a music lover and a dancer since I was 10,” she said. “I remember listening to KYA in my bedroom.”

By the time she was in college, “I was throwing little dance parties, mixing, not just playing one album,” and she has never stopped. Wherever she traveled, she went to dance clubs. And when she moved to Petaluma 25 years ago, she started giving parties.

She bought a sound system. She started doing live gigs. And then, nine years ago, Twist & Shout was born, “Petaluma’s funky dance jam.” Now Lunch Beat has joined the fun.

“It’s just one more great way to get exercise,” Richman says. “Like dancing in your living room, only better.”

The next Lunch Beat starts at 11:45 a.m. Wednesday, Aug. 15, at Petaluma Valley Athletic Club, 85 Old Corona Road. Cost is $5. The next Twist & Shout is at 8 p.m. Saturday, Aug. 18, at Bodyworks Yoga Studio, 490 Second St. Cost is $10. Call 695-9268 or visit Twist & Shout Petaluma on Facebook.