How to exercise while horizontal. NASA

If you have the stamina to lie in bed for 70 days straight, NASA will pay you $18,000 — no joke.

It's called the "Bed Rest Studies — The Exercise Study (CFT 70)."

They say the study is "designed to minimize loss of muscle, bone and cardiovascular function through high intensity interval-type aerobic exercises on alternating days, with continuous aerobic exercise daily."

Here's the full description. They write:

This study will show how much your body, tilted down slightly with head down and feet up, for 70 days, 24-hours a day, without getting out of bed, except for limited times for specific tests, is like an astronaut’s body during the weightlessness of space flight. Watching you will help scientists learn how an astronaut’s body will change in weightlessness during space flight in the future.

During your off time you get to play on your phone, read books, Skype, take online classes, or anything else you want ... as long as you don't stand up. I'm pretty sure you would have to have a catheter and a solid-waste collection bag, and NASA has created a special shower gurney for washing.

After the testing phase you will have another few weeks of recovery days in which the scientists study how your body adapts to being out of bed. They pay $1,200 a week for the duration of the test — usually 15 weeks.

Roni Cromwell, a senior scientist who worked on the study, explained to Forbes: "We also ask them [test subjects] to do tasks that astronauts would do when they land on a planetary surface. Simulate getting out of a vehicle.

"Moving heavy objects at a short distance. This gives us an idea as to their functional capabilities."

Heather Archuletta, a previous study subject who's now a NASA contractor, told Forbes: "The day I got up, after being in bed for 54 days [the study was cut short by Hurricane Ike], my feet hurt like crazy walking for the first time! But, I reminded myself, this is what astronauts go through, too."

To apply, fill out this form.