This question can be answered by an examination of illnesses and their effects. All the information here pertains solely to religious Wiccan ritual and is generalized- you must use your own judgment. Be attentive to your body. It usually knows what's best. Forcing yourself to perform rituals while facing challenging illnesses and conditions can be dangerous. The physical aspects of sickness are usually the most obvious. Some illnesses create a pronounced lack of energy. It may be difficult to walk across the room, let alone cast a circle. In such a case, a ritual with limited physical activities is clearly indicated. Cast on broken feet, hands, arms, or other limbs may or may not restrict your ability to set up an alter or hold a book of shadows. At least in doing so you wont further endanger your health. Your movements in the circle, however, may be limited, so avoid slavishly following ritual conditions. If your health care practitioner or doctor has ordered bed rest, or told you to stay off your feet, follow his/hers instructions. Either adapt the ritual to a purely verbal and mental experience, or wait until you've recovered. During many types of illnesses (including colds) a pronounced change of consciousness often occurs. Slight dizziness, sinus pressure, elevated temperature, pain and other symptoms can create the most remarkable shifts in consciousness -- even in people who haven't attempted to mask the symptoms with drugs. This type of consciousness can lend the ill Wiccan a radically different perception of the world; one which usually hinders ritual works. If your staggering around and cant seem to concentrate, its best to avoid working with magickal athames, flames, incense, and other potentially dangerous magickal tools. If your apt to 'space out' it's best to simply sit or lie comfortably and do little else. You might whisper a prayer to the Goddess and/or the God, meditate upon an image, or perhaps draw a symbol and concentrate on it. If you cant simply concentrate long enough to formulate any type of ritual, its probably best to let it go for now and resume ritual workings when you're once again able to do so. (All this information I got from "Living Wicca a Further Guide for the Solitary Practitioner by Scott Cunningham.)
