Kate Middleton has stolen the spotlight in recent red carpet appearances by showing up in sexier, more daring gowns and sky-high heels that show off her slim, toned figure.

Now British media are reporting they've obtained the Duchess of Cambridge's secrets to staying so fit and toned, and it could be good news for commoners without a royal budget or a royal personal trainer.

PHOTOS: Kate Middleton's Style

Middleton, 30, reportedly stays fit with just a ball, a set of dumbbells and one hour per day.

Calling it the Duchess's $15 workout for the price of the ball and dumbbells combined, British magazine Now reports that Middleton, the wife of Prince William, 29, trains herself, without the assistance of a trainer or fancy gym.

"Kate does an hour's workout every morning using the gym ball and dumbbells, which includes some core exercises like squats, sit-ups and arm curls," a royal source tells the magazine.

Middleton was an athlete in high school and recently showed off her sporty side in a surprise visit to the Olympic Park in Stratford, East London, where she took the field and held her own with the British Olympic women's field hockey team.

The Duchess, whom Now claims is a size 6, has also been spotted staying active by cheering her husband and brother-in-law, Prince Harry, on at the polo field and taking the couple's new dog, Lupo, on long walks.

The no-frills approach to exercise, while not confirmed by the Palace, would fit in well with the everyday lifestyle preferred by Middleton and her royal groom.

The couple are said to have shed royal servants in favor of going it alone and Middleton herself has been spotted doing the couple's grocery shopping and filling her wardrobe with visits to mass retailers like TopShop in London.

Not reported in the Now magazine article is whether or not Middleton's exercise regime is part of a training program for any particular race.

Last month as Prince Harry presented medals to the winners of the 2012 London Marathon, the prince, with a smile on his face, proclaimed that Middleton and William would run in next year's marathon.

"What's fantastic is my brother and his wife will be doing it next year," Harry told BBC's Sue Barker, during a live interview broadcast across the country.

Neither Middleton nor William commented, but a Clarence House spokesman later confirmed that Harry's remarks "were said in jest."