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Princess Diana’s Niece Reveals Her Secret to Getting Sculpted Abs

Lady Amelia shared her go-to workout in a sweltering social media post.

Cailey PetschHealth and Beauty Intern

PublishedJun 25, 2026, 5:26 PM EDT

UpdatedJun 25, 2026, 5:26 PM EDT

Updated Jun 25, 2026, 5:26 PM EDTPublished Jun 25, 2026, 5:26 PM EDT

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Lady Amelia Spencer Mallett shared the sweltering secret to her shredded physique on social media.

On June 25, ​Princess Diana’s 33-year-old niece shared a photo on her Instagram story showing how she achieves her lean physique.

She and her twin sister, Lady Eliza Spencer, are the daughters of Princess Diana’s younger brother, Charles Spencer, 62. Both Amelia and Eliza are influencers and models.

In the photo, ​Amelia poses for a mirror selfie, glistening with sweat as she turns to the side to show off her toned abs and arms. She picked the high-energy track “Discipline” to play over the post.

“40 degree Inferno HIIT Pilates,” she wrote in the caption, referring to high-intensity interval training, a favored fitness method among Hollywood’s top talent.

HIIT involves rapidly alternating between intense aerobic exercises and brief periods of rest and is often combined with Pilates, a lower-impact exercise system.

Inferno Hot Pilates is a full-body workout designed by fitness instructor Gabi Walters and performed at temperatures above 95 degrees Fahrenheight. (Lady Amelia, being British, presumably described her session as taking place in 40 degrees Celsius, which converts to 104 F.)

“Living in my @oneactive,” she wrote over the selfie, tagging fitness clothing brand Oner Active. She also tagged her husband of three years, Greg Mallett, a 36-year-old lifestyle coach with whom she often exercises.

​On April 15, Mallett shared a video on his Instagram of the couple lifting weights and running on treadmills. They also frequently share photos of their spa and sauna visits.

Her black Oner Active bike shorts resemble one of her late aunt’s wardrobe staples.

Princess Diana often wore similar streetwear—long before the term “athleisure” hit the cultural zeitgeist—after her formal separation in 199s from Prince Charles, now King Charles.

​Charles Spencer shares the twins and his eldest daughter, Lady Kitty Eleanor Spencer Lewis, 35, with his ex-wife, British model Victoria Lockwood.

Lady Amelia and Mallett were married in 2023 on a mountaintop in the Western Cape, South Africa, the country in which she grew up.

For her wedding, she wore a custom Atelier Versace gown.

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“I think [Diana] would be very proud to see me on my wedding day,” Amelia told Hello Magazine. “I know the Versace family also absolutely love Diana, so there’s a very special connection that we have.”

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Cailey PetschHealth and Beauty Intern

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