By Jen Murphy

Marah Kabaservice jokes that she’s a closet exerciser. You won’t find the 50-year-old nurse practitioner at the gym or in spin class. She finds more motivation hula hooping and doing jumping jacks in the privacy of her home in Rutledge, Tenn., a town near Knoxville.

As an unathletic teen, Ms. Kabaservice was turned off from fitness by the forced activities of high school gym class. She flailed through dodgeball, softball, even warm-ups. “I nearly flunked P.E. because I couldn’t run four laps around the track,” she says. “By my 20s, I was a complete slug, smoking a pack of cloves a day.”

Knowing she had to make a change, she tried running again. Away from the judgment of peers, she found she actually enjoyed exercise. “When I was by myself, I could focus on myself,” she says. “My workouts became my time to zone out and think through my problems.”

As she logged more miles, Ms. Kabaservice quit smoking and took up new workouts, like jump roping and her current passion, hula hooping. She’s gone from an exercise-hater to a never-miss-a-day obsessive. Exercise, she says, has been her saving grace the past six years as she’s cared for her aging father, who suffers from a debilitating neurological disease. At least one week a month, she flies to her parents’ home in Melbourne, Fla., to give her mother some relief from caregiving duties. Last year alone, she says she flew 64,000 miles back and forth.

“As I worry more about my parents, I’ve gradually upped the intensity and duration of my workouts at home, because it helps with my anxiety,” she says. “The exercise also helps to keep me in good physical shape so that I can help my bedridden dad with basic activities such as sitting up on the edge of the bed.”

Whenever she’s feeling stressed, she picks up her hula hoop. “It’s a healthy way for me to work out my emotions,” she says.

The Workout

Ms. Kabaservice works out six days a week at 5:30 a.m. Her home routine takes around 85 minutes. She spends about 50 minutes of that time hula hooping. She doesn’t just use the hoop around her waist—she also circles it around her glutes and upper thighs and mixes up the speed.

“I try to make it a whole-body workout and move my arms in a circular motion at the same time,” she says. Between bouts of hula hooping, she will do 10 minutes of jumping jacks and 10 minutes of elbow-to-knee touches with 2-pound dumbbells.

She stopped running the country roads near her home due to stray dogs. She now walks the perimeter of her 12-acre property for an hour, about six laps, once a week. She recently took up hiking in nearby Panther Creek State Park.

When in Florida, she uses an old exercise bike in her parents’ home, walks around their neighborhood and spends 30 minutes a day helping her father do a series of range-of-motion exercises. “Moving my dad into his recliner is a workout in itself,” she says. “I find I burn more calories in Florida and I’m not even hooping.”

The Diet

Ms. Kabaservice says the stress of caring for her father, combined with the physical strength required to help him around the house, often leaves her ravenous. She spent all of December at her parents’ home and says she ate an entire box of Cheerios each day on top of her usual meals just to be able to maintain her weight.

Normally, she averages 2,800 calories a day. “I’m a vegan in a land of carnivores,” she jokes. She starts the day with oatmeal topped with pecans and almond milk. When working, she rarely has time for lunch. She instead snacks throughout the day on olives, nuts and blueberries. Dinner is often a large salad topped with avocado, legumes and nuts. Her vices are, depending on the time of day, Hawaiian Punch or bourbon.

The Gear & Cost

“The beauty of working out at home is that I don’t have to invest in trendy exercise garb,” she says. “I wear threadbare shirts and ratty shorts.” She bought her weighted hula hoop for $43. She buys Saucony sneakers.

The Scoop on Hoops

If you want a full-body workout, a hula hoop might not be the first piece of equipment you grab. But 30 minutes of hooping is comparable with power yoga, boot camp, cardio kickboxing and other group fitness classes, a 2010 study from the Exercise and Health Program at the University of Wisconsin, La Crosse showed. It burns a similar number of calories and gets people to similarly elevated heart rates.

On average, participants burned 210 calories. The study used a weighted hoop and participants had some experience hooping.

Rocking your hips from side to side to keep the hoop circling around your waist at a constant speed activates core muscles. Get creative, and it can become a full-body workout, says Getti Kehayova, a hula hoop fitness instructor in Las Vegas.

“I have everyone do squats while hula hooping,” she says. “It helps engage the quads and also helps with balance and posture.” She has students hold a 5-pound dumbbell in each hand and do arm raises to the side and front while hooping to work their shoulders. “To engage your core to the fullest, get your speed going for 30 seconds, then spin at normal speed, then spin fast again,” she says.

If you’re still a beginner, Rebecca Burton, a hula hoop fitness instructor in Gainesville, Fla., suggests alternating regular hooping with arm exercises. For example, to work your shoulders and triceps, reach your arms above your head, hands together, and spin the hoop around both hands while keeping your arm muscles engaged, Ms. Burton says.