Training is extremely physically and mentally demanding, and takes place during both daytime and nighttime. Sleep is permitted for no longer than three hours a day, but only if the right is earned. The right to eat must also be earned; before being allowed to eat, soldiers must successfully climb a rope, do five pull-ups, ten push-ups and run two miles in 18 minutes or less wearing full combat gear, then duck walk to the mess hall, after which they are given 30 seconds to eat.