If you are in Houston or can get there NASA may pay you $17,000 to stay in bed for 90 straight days. Seriously the bed-rest experiment, to take place in the Human Test Subject Facility of Johnson Space Centre, is designed to allow scientists to study some of the effects of microgravity on the human body. Participants will spend 90 days lying in bed, (except for limited times for specific tests) with their body slightly tilted downward (head down, feet up). Every day, they will be awake for 16 hours and lights out (asleep) for 8 hours.
Jokes aside, astronauts who've spent lengthy stays in space have suffered serious consequences. Our bodies have evolved to deal with a certain amount of gravitational force but if you reduce g then muscles atrophy and bones lose their density. It can take astronauts/cosmonauts (and soon taikonauts I presume) months to readjust to the Earth's gravitational force.
If you're still interested, you'll have to pass a standard Air Force medical and take a blood test. Apparently you can do what you like to alleviate the boredom but you must stay prone...
Right, now where’s my passport!