“When she gets down in the pool, I can just see a different glow in her face,” says Slaton’s nurse Tisa as she watches her swim

Tammy Slaton is floating “like a butterfly” through the water as she tries out her first pool aerobics class.

The 1000-Lb. Sisters star, 35, is working to lose weight, which means changing up her diet and giving workouts a try. And her first water aerobics class is an immediate hit.

In this exclusive clip from Monday’s episode, Slaton slowly walks into the pool before joyfully sliding in.

“When she gets down in the pool, I can just see a different glow in her face,” her nurse, Tisa, says. “She’s in the water, and she can do movement.”

Slaton joins in the class, moving her arms with the water weights and doing kicks and spins.

“She’s flopping arms around, she’s kicking her legs, she’s flopping her a– around, she’s doing it all,” Tisa says. “And she floats! Like a butterfly! I thought she was going to fly away.”

“I’m weightless,” Slaton says, happily.  

As the class progresses, though, Slaton loses interest in doing the movements, preferring to relax on the side.

“You gotta do the exercise! C’mon sister! C’mon sister!” Tisa tells her. “Tammy, you gotta side step. You ain’t doing what the woman wants you to do.”

After the class, getting out of the pool is a struggle. Slaton slowly walks out and ambles over to her walker, but then refuses to try going back into the locker room.  

“I can’t walk back there, the floor’s wet,” she says.

Frustrated, Tisa says “she would’ve had me push her from inside the pool, out of the pool, back to the car, if she had her way.”

But Slaton eventually relents, and starts walking back with her walker.

“When you’re not in the pool, it’s like, hard to get around,” she explains. “Carrying around 640 lbs. is a lot on your body, on your knees, on your feet, your ankles.”

New episodes of 1000-Lb. Sisters air Mondays at 10 p.m. ET.