We are body and soul. The body's aches and pains are recognizable and touchable. The soul on the other hand is mysterious, can't be seen nor physically touched...
"Verily I say, the human soul is exalted above all egress and regress. It is still, and yet it soareth; it moveth, and yet it is still." (Baha'u'llah, Gleanings from the Writings of Baha'u'llah, p.161)
Based upon my belief in the Baha'i Faith, the soul is sick if it does not show forth God's attributes, which are love, compassion, kindness, forgiveness and a whole other array of godly virtues. A person who does not show forth these attributes has an unhealthy soul, trapped in the world of self and is therefore unhappy!
One of my favourite prayers:
God! Refresh and gladden my spirit. Purify my heart. Illumine my powers. I lay all my affairs in Thy hand. Thou art my Guide and my Refuge. I will no longer be sorrowful and grieved; I will be a happy and joyful being. O God! I will no longer be full of anxiety, nor will I let trouble harass me. I will not dwell on the unpleasant things of life.
O God! Thou art more friend to me than I am to myself. I dedicate myself to Thee, O Lord.