How about that overachieving Duchess of Cambridge, everybody!

Kate Middleton gave birth to Prince George on July 22 and she was scheduled to return to public duties on September 12, as co-guest-of-honor with Prince William at the inaugural Tusk Conservation Awards.

But Kate — like Miley, and yet never like Miley — can't be tamed, and she actually headed out with Will today (Friday, August 30).

As the officials from Clarence House tweeted earlier, "The Duchess of Cambridge will attend the Ring O’ Fire #Anglesey Coastal Ultra Marathon with her husband The Duke of Cambridge today."

According to E! News, William was expected to meet with participants and volunteers to help kick off the event, but Kate's appearance comes as a pleasant surprise. 

(Head here for "live updates" from the U.K.)

Credit: James Whatling/Splash News Photo: Kate Middleton and Prince William Attend the Ring of Fire Marathon in Anglesey, Wales, on Aug. 30, 2013

Although this is Kate's first public event since giving birth, it's not like she's been hiding inside.

Us Weekly has a photo of her on a grocery run from August 26, and they quoted a source who said the naturally thin mom has "hardly done anything to lose the [baby] weight ... she looks incredible."

She’s reportedly continuing with her yoga, but she's not dieting or anything. She just has good genes!

What about the royal baby himself? Prince G's christening will be held sometime this fall, E! noted, when we'll get to see more official photos of the lad. Here's hoping for red hair like his Uncle Harry!

Since we can’t help comparing princesses, one of Princess Diana’s first post-baby public appearances was at Prince William’s christening on August 4, 1982. Unfortunately, Prince George won’t be able to carry on one of the Royal Family’s traditions: wearing the same christening robe as everyone else. The 167-year-old Honiton lace and silk gown has suffered some wear-and-tear during 30 baby christenings, starting in 1841, and Queen Elizabeth II commissioned a replica for Prince Georgie (as his grandfather, Prince Charles calls him). Let’s just hope they forgo one other tradition: eating year-old wedding cake at the ceremony. That’s what the family did on baby Will’s big day — they munched on Charles and Diana’s 371-day-old cake.

What do you think of Kate's first post-baby event look? We need that green Ralph Lauren blazer...

Sources: @ClarenceHouse, E! News, Us WeeklyE! News