To perform a somatic shake, find a comfortable space, start with gentle movements like stretching to warm up, then allow your body to shake naturally by initiating movement in your hands and wrists, gradually letting the shaking spread throughout your body, focusing on deep breathing throughout the process, and slowly coming to stillness once you feel ready, all while paying close attention to your body's sensations and letting go of tension with each shake; you can either stand with feet hip-width apart or sit depending on your preference.