Grief causes the body to stay in a constant state of "stress mode" it is the same as the fight or flight response that the nervous system reacts to danger with.
The brain releases chemicals that change the way we think and feel. Once it starts, it is like a snowball rolling down hill. It causes many physical changes in our bodies and a negative mindset.
The stress chemicals shut down parts of the body not needed for strength, speed, or survival including cognitive thinking, digestion, sleep, bladder control, and more.
There is however a way to counter the fight or flight response with what's called the relaxation response. It may take some time to get out of "stress mode" but here is a technique that works for all of my clients.
The slow deep breaths will flood the body with fresh oxygen and take you out of fight or flight response by telling the mind that the threat is gone or was not real.
Focusing on gratitude will open your heart and cause happiness to take over your state of mind and trigger the relaxation response by releasing seratonin and dopamine, the "happy chemicals".
Focusing on your senses will cause you to ground yourself in the present moment and be in the here and now and stop you from focusing on the past or the future.
A big part of healing is understanding why we feel the way we do and how the body reacts to what happened.