Easier than it looks...
For an exercise that you can do at home what better than something to hit multiple parts of the body at the same time, a compound stability exercise that has elements of squat, hip raise, balance, core and the fantastic stabilising results that ensue...
It is quite tough and you will fall over... a lot ! so make sure you do this one either in a padded cell or if you're not stir crazy then do clear some space in whatever room you do the exercise in... cant have you hurting yourself now...
Anyway, enjoy the exercise and feel the benefits at the;
Spine erector muscles (Lower back predominantly though )
BootCamp Military Fitness