It's no secret that Pippa Middleton loves being active, and now she's using fitness for good.

Pippa and her younger brother, James Middleton, departed from California this weekend for the competition. She will be raising money for the British Heart Foundation and The Michael Matthews Foundation, the Daily Mail noted.

In a team of eight, 30-year-old Pippa is the only woman. They will travel from California to Annapolis, Maryland.

The 3,000-mile trek, which is known as Race Across America, will be demanding and tiring, and Pippa spoke about how she was going to protect her bum.

"I think every cyclist including me will be layering it on," she said. "Once we get going it's non-stop with very little sleep. It's nerve-racking but exciting all for a great cause."

She also said chamois cream, which usually is made up of shea butter or aloe vera, will be her go-to.

The race has been going on for about 32 years, and in that time, less than 200 people have finished. The race will see the cyclists climb 100,000 vertical feet through the route. The team will split into two groups of four to ride for five to six hours at a time. This will give the other team a chance to rest and eat.

While Pippa said she wasn't worried that she was the only woman on the team, James talked about the real challenges they'll face.

"We'll have other things to worry about rather than personal hygiene," he said.

Pippa and James started training for the competition eight months ago.

Rick Boethling, the organizer of the race, said that Middleton is only one of the few women to ever take part in the event.

"Riders regularly hallucinate through lack of sleep," he said. "Pippa's a tough cookie."