As one sits and realizes the impermanent nature of thoughts and feelings and begins to get a flavor of the background space one might begin to feel less solid in their identity altogether. We invest so much in our jobs, our relationships, and our good works or bad habits that they at times identify who we are. Our roles along with our habits and thinking patterns construct our personalities and hold our egoic selves together. Sitting in meditation puts holes in the fabric as gaps will naturally arise. Continually coming back to the breath cuts any fear and allows the space for seeing habitual patterns. Bringing habit into consciousness creates change and over time a long term behavior can dissolve. The more strongly we identify with something we are letting go of, the scarier it is to the body. You may feel like you are literally dying. If the pattern was established in infancy as a coping skill or a way to be accepted in the family you may have a fear from then that if you change you will be ostracized by the group and you will die, which as an infant you were dependent on your parents for survival, but that is not the case now. Take a deep breath and release any fear.