Please take note, now that you have been made well, give up your sins or something worse may overtake you. What we hear Jesus saying to the individual whom he had just healed may sound rather odd to our ears. Was Jesus associating the man's former condition with the man's sinfulness? Was Jesus implying that the man’s illness had resulted from his sins? If this is what he was saying, wasn't Jesus contradicting himself? (When later on he will be asked whether the blind man healed by him was blind on account of his sins or his parents' sins, he will reply in the negative [cf. John 9:2ff]). It would be safe to assume that Jesus was not contradicting himself here. Neither was he implying that the man’s sickness had been caused by his sinfulness. Rather, Jesus was merely stating a fact: that we are all prone to sin (cf. Romans 3:23). Moreover, Jesus was aware that when pressed to a corner by sickness, even the strongest human person can reach a breaking point (the story of Job in the Old Testament is a perfect example). The individual healed by Jesus had been paralyzed his entire life. His condition had made him to depend on others for his livelihood. If he was a Jew, it was highly likely that he had heard people talking about sickness and poverty as consequences of sin or as indicators that God had withheld his favor from an individual. Handicapped and unable to participate even in the most ordinary of human activities, he might have bought into the idea that God had withheld his favor/blessings from him. With no one to plunge him into the pool whenever the waters were disturbed year after year, a wave of desperation might have descended upon him. And as he lay there beside the pool day after day staring into nothingness, one can only imagine the thoughts that were playing in his mind. Circumstances might have led him to buy into the popular belief of doubting God's existence and love for him. 
Jesus did sympathize with the man and gave him back his life. He too knew that the glory of God is a human person fully alive, and that this man's condition might have become an impediment to him feeling fully alive. However, Jesus reminded him that as unfortunate as his condition was, it was not the worst! He was physically handicapped, but he still had faith (otherwise he would not have been at the pool side). The worst that can happen to a person is being separated from God. For without God in one's life, life loses meaning since there remains nothing for which to live. Separation from God takes place when one persists in sin. The healed man had to be careful not to fall in sin even as he reveled in his newfound fullness of life.