One method is to visualise a ball of white light above your head, with the light spreading in all directions. Imagine the light spreading through your body, completely dissolving away all sickness and problems. Concentrate on the image of your body as completely healed and in the nature of light. This type of meditation is even more powerful when combined with visualising holy images and reciting mantras. I often tell my Christian patients to visualise the light as Jesus, with the light emanating from him.
Deities can be in peaceful or wrathful aspects.
If you are not comfortable with these images, you can use other objects such as crystals, or simply visualise all the universal healing energy absorbing into you, transforming your body into light, and imagine yourself as totally healed. Over the centuries many people have used these methods and have recovered from their illnesses, even from conditions such as leprosy, paralysis and cancer. The aim of these practises is to heal the mind as well as the body, so that the diseases or problems will not recur in the future. Also, many diseases are associated with spirit harm. Lamas and other practitioners will often recite certain prayers and mantras or engage in ceremonies to stop the spirit harm and allow the person to recover.