Lie on your stomach and lift your head up while keeping the legs relaxed on the ground. Check what you can see using just your eyes and neck and slowly add a lift with your back upwards while still keeping your legs and arms relaxed. Now when you are up, take a pistol or a knife out of your bag or belt and put it back again a few times and rest. Work on your awareness to your face muscles so you can stay relaxed in uncomfortable positions and so increase your effectiveness and mobility. Now place your hands over your neck and interlace your fingers to simulate handcuffs. Work on looking around and than getting up and down again a few times to see how you can best move in this restriction and add to this placing your feet together and doing the same. You never know how you will end up so keep your work free and see how you can think in tight quarters. Another way to do this in a group is to have one in the middle work on getting up and down or outside a circle while they are pushing him down or striking or using sticks or chains to cause pain. This can be hard on the mind as well as for the body so you should remember not to harm yourself.
To work on your posture you can place your hands over the back of the neck and tense against your back urching upwards slowly with your breath a few times. Move your spine against this light resistance on the floor and than change the hands to the ching and push up as you resist with the neck and back. Remember the work is here for you. Not you for it.