Psalm 38

The foolishness of sin affects us in more ways than just spiritually. Allowed the fester the spiritual works of death begin to manifest themselves in our physical bodies. David recounts his infected wounds, draining fever, and chronic pain that had left him exhausted. Though we don't know the sin he comitted that led to this illness we do see his confession in verse 18 along with his plea for God to stay near.  Both are examples of how we should bare our sins to God.
Stuart