When doing different kinds of mindfulness work, physical sensations of discomfort will arise at various times. The sensations may range from mild tingling to a more intense experience that can make it difficult for you to remain focused and attentive to your experience. You may ask yourself: “Is it okay to move when this happens?” And the answer is, of course. You can decide to move at anytime.
However, before you immediately decide to move, you might want to examine how the body actually feels. There is some virtue, in fact, in not immediately changing your posture and reacting or fleeing from the experience (except to re-establish, the upright, stable, dignified sitting position).
If the sensations are not too intense, you might want to “stay with” the experience and allow them to enter the field of your awareness as part of your experience that is unfolding in the moment. If/when you do choose to move, you may wish to become as aware as possible of what parts of your body are moving, and to what degree and how you are moving your body. Basically, bring an exquisite sensitivity and gentleness of awareness to the part of the body you are moving. Observe how you are moving it—even perhaps playing with being extra slow and soft with your movements.