There are times when there is no breath to have or light to guide your way. Lie on the ground in your house or office and crawl on the floor to the door using only one breath. Find a window or opening to breath and continue if possible and learn to calm yourself and avoid the panic from taking over. Do the same exercise with your eyes closed from other places and find the way with your body and limbs. Keep close to the floor to avoid fire or shooting. Next do the same on your hands and feet or pushing someone with you and remember why you do what you do. Find a way.

For wrist, fist and shoulder relaxation you can stand on fists and feet with your belly up and jump backwards and forwards lifting all limbs off the ground at the same time. the same goes for moving close to the ground on your hands and feet or fists and feet as you can do so much more and rely on your alignment and coordination to get the job done. Do this and work on your relaxation and alignment as you keep from harm.

And Smile.

Many times we are full of anger or other emotions that pull us off course. One of the ways to calm yourself is to walk and breathe scaling up and down from one breath per one step to one breath per two and so on and if you are really tense add a pause state between the inhale and exhale. Your body must relax to do the work and especially for the breath holding work and it will allow your mind to relax as well and this will put you in this moment. You will be here.
Vladimir writes in his book the Systema Let every breath we should tense and relax our bodies before getting out of bed to awaken the body and mind and to have a more healthy awareness. To do that you can tense each part at a time using your breath as a guide, tensing opposite muscles in turn (extend vs contract) and move the tension in waves in the body. Another way to do this is to work on your tension while in an uncomfortable situation. Alone by tensing different parts while balancing on one leg with your eyes closed and your body tiped to one side, as you are in a lever and looking for a way out by creating more room around you with the tension and than releasing through relaxation and also while rolling or in the air between. Make sure not to harm yourself and not to do things against your common sense.
Stand on one leg as you do in mid step and start to move using the foot and the leg without hopping. Move about until you feel the blood flowing and than start to hop in place. Hop forward and backwards, side to side as you face the same direction and in place in a circle both ways. Once you are familiar with your way of doing this add a friend with a stick or anything else have you pushed and pulled in various hights and your job is to remain mobile and unharmed as you hop all the time. This is a good way to reach better freedom of movement while on the move and gain better alignment in marksmanship while moving. Keep your breath moving and your eyes relaxed.
In wrestling or any other fun thing you choose to do you need to pay attention to your teeth. In sport I think it is not allowed to bite during the activity but if you are learning to use all that you have and to survive it is of importance to know that you can use your teeth and voice to more than food and voicing your opinion. For example there are a lot of holds people enjoy using where your teeth are forcefully brought to your partners neck and a simple bite will set you and his mind free. A hold where you are smothered to his side will release if you tickle his ribs with your teeth and a loud shout can unnerve many if issued without bodily tension while you are held. Think about what you can do to survive and protect your loved ones. USE your head, all of it.
A simple add-on to the four basic drills of push up, sit up, leg raise and squat is to perform a simple action while you are doing the drill to broaden your awareness and clean yourself from more tension. For example to turn the hip left and right like a grandfather clock pendulum or a more chalanging one is to lift the hip sideways and the leg as well as you squat and get up (Sailor walk which I reccomend for relaxing and learning to use the hips better). Another example is to roll your forearms in front of you as if you are reeling a heavy rope one way on the sit up and the other on the way down and during the push up to rotate your leg in the air one way and the other on the way up.

Make the drill your own.

You know your body aligns and tenses in a different way when you try to push the ground away in a push up or try to push yourself off the ground. You can work this to learn to relax more and to align in the upright position by squatting slowly with your hands in front of you and someone either pushing your hands up or down or to either side. This forces you to adjust your spine muscles (the one erecting and moving the spine) according to the tension and allows you to become aware of a lot more and learn to control your posture and tension swiftly. You can do the same with big rubber bands or anything heavy around you.
A simple way to stay warm and awake in cold conditions like being wet in the rain or stuck in a plane with sub zero temperatures is to schedule an interval like one hour or so depending on the conditions and do some push ups and tell your body to warm up and keep the blood flowing. This is like speeding your breath before a sprint to tell your body to prepare for the effort so it will pass with less tension and it works. You can also tense and relax the body in different ways to keep your mind and body awake if the job requires you to keep from moving too much.
Stand against a wall or a pole and work to defend yourself (using a knife as well as your body and mind) and get away from attacks where you have to also draw the knife from various positions such as with the other hand, From your coat, from your back and so on. See how you can move to avoid getting hit as you draw the knife if you feel you will use it for intimidation or cutting and remember your life is more important than the knife. Be mindfull of your breathing and keep your eyes relaxed.