Prince Harry is preparing to join four wounded soldiers as they try to ski to the North Pole.
The team will set off on the 200 mile trek in April, and it will take four weeks to complete.
Harry is planning to join them on part of the journey, and is working to get as fit as possible before they start.
They are hoping to raise lots of money for one of the Prince's charities, called Walking with the Wounded, which helps injured troops.
It's going to be really hard work. Each man will pull a sled weighing more than 100kg in freezing temperatures as low as -50C.
Harry also has another important mission - to get back in time for his brother, Prince William, and Kate Middleton's wedding in London on 29 April.