Kristin Cavallaris Intense Three-Hour Bikini Workouts!

Kristin Cavallari of The Hills fame appeared to be in the best shape of her life on Thursday as she walked during Miami Swim Week.

The 39-year-old jewelry designer looked very muscular as she posed in a leopard print bikini with a see-through sarong skirt as she added nude high heels.

'Kristin worked out three hours every single day to make sure her body was in top shape, she really to get there,' a source told The Daily Mail.

The three hours was broken up over the day as she 'spent an hour and a half lifting weights in the gym in the morning, then went for an hour and a half power walk later in the day,' added the source. 

Cavallari is 5ft3in tall and currently weighs around 114lbs. 

'She always works out but she went the extra mile to prove that she is still hot as she approaches her 40th birthday next year,' added the friend. 

Cavallari walked the runway wearing RESA's Serpent print bikini styles paired with jewelry from her own brand, Uncommon James. 

Turns out the blonde beauty was also 'nervous as hell' to walk almost naked in front of hundreds of people at the Mondrian South Beach.

'She had the shakes, she was sweating because she was scared to walk the runway, it took a lot of confidence to do that and she stepped up to the plate,' said a friend.

She could be seen backstage taking deep breaths to prepare for her catwalk moment in a video she shared to her Insta Stories. 

The next morning Cavallari appeared exhausted as she applied skincare after a 'long night' in Florida. 

RESA and Cavallari's Uncommon James made their runway debut together during Miami Swim Week: The Shows at The Mondrian South Beach. It was the first-ever fashion show for both brands. 

The show took place on the waterfront as resort wear and statement jewelry were both represented.

Cavallari showed off her necklaces, rings, bracelets, earrings and an anklet using sculptural metals, shells, pearls, and warm gold accents from Uncommon James.

The reality TV star has said the summer line was inspired by 'Mediterranean summers and vintage markets.'

'I wanted the collection to feel relaxed, sexy, and wearable beyond just vacation,' said Cavallari in a press statement.

'The layered statement necklaces are definitely my must-have. I love how they instantly transform even the simplest outfit.'

Cavallari discovered RESA last year and she became a genuine fan of the brand.

The runway showcased RESA's latest summer collection styled with Uncommon James jewelry, blending bold prints with layered accessories.

For RESA founder and designer Suzanne Marchese, the collection was inspired by summer travel and the desire to create pieces that feel both timeless and exciting. 

'We've stepped outside our comfort zone with prints that are more daring, vibrant, and expressive, bringing a fresh level of excitement while still staying true to our signature sense of timeless style.' said Marchese.