Osbourne embarks on extreme fitness regime

Reality TV star-turned-filmmaker Jack Osbourne has embarked on an extreme fitness program - the same training regime used by U.S. Navy SEALs.

The son of Ozzy and Sharon Osbourne recently began training outside Crossfit Hollywood, where he was put through his paces by a personal trainer.

The strenuous exercise routine includes weight lifting, endurance running, gymnastics and cardio work and Jack is already feeling the pain - he posted a photo of his cut-up hands on Twitter.com last week.

But the 25 year old has already been tipped for fitness success - one of his coaches tells WENN, "Jack is really agile and knows his body well, he picked up the exercises quickly. He should do well at Crossfit."

Osbourne has been dedicated to keeping in shape since 2005, when he dropped 50 pounds (22.7 kilograms) in preparation of his extreme sports TV show, "Jack Osbourne: Adrenaline Junkie."