It's the new extremely cool trend used by famous sports and movie stars: freezing yourself to stay feeling young.
Cryotheraphy is a 2-3 minute full-body freeze in a sauna-like chamber where nitrogen-iced air circulates at minus 200 degrees Fahrenheit.
It's chief aim is to boost metabolism, but it is also said to have benefits that range from stress relief to reduced inflammation, better sleep and improved skin tone.
Footballer Cristiano Ronaldo is said to travel with his own cryotherapy chamber to keep him in mint condition, while actor Daniel Craig is believed to have used cryotherapy while shooting new James Bond movie Skyfall.
During a session, your body recognises it's freezing so it increases its flow of oxygen and blood. When the body returns to normal temperatures, it pumps blood back to the tissues which stimulates oxygen and nutrient supply, resulting in tissue healing. The extra work for your body burns calories, and the tissue healing means firmer, glowing skin.
It started in Japan and is now becoming increasingly popular in the US where sessions cost between $80-$90 (£55). KryoLife, the leading cryotherapy centre in New York City, claims you can burn 800 calories in just one session.
A woman who used the chamber there, said: "I can go and I can have 45 minutes of an amazing workout session that I didn't have before. I am amazed with myself. I'm like a superwoman now."
Some doctors, however, say that frostbite is still a possibility.