Jesus 'penalty for sins' need to include physical and emotional pain because God sent Him to us in human form. Jesus had to suffer the same way an ordinary human being has to suffer when crucified on the cross.

Jesus had come to serve not to be served. He had to suffer humiliation and rejection from the people he had loved.  He did great things like healing the sick, giving sight to the blind, making the lame walk, etc. but the people still did not believe Him.  

I think that Jesus had to suffer in the hands of His people and had to die on the cross, be buried and be resurrected on the third day so that His people will believe that He was really the Son of God that was sent to save the world from eternal damnation.

When I'm in the state of pain and discouragement, I always remember of how Jesus suffered on the cross and died for our sins.  I always compare the pain I felt and the pain Jesus felt on the way to calvary.  That way I realized that my pain was too small compared of Jesus' pain. It always gave me strenght and joy by remembering Jesus on the cross.