joy is the thought of the coming Kingdom

"...we are told that the Lord Jesus 'for the joy that was set before him endured the cross.' He looked forward to the consummation of God's purpose, and saw glory instead of shame, joy instead of sorrow, a righteous world in place of a wicked one, and instead of the crowd mocking enemies he saw a vast assembly of adoring brethren, every one of them saved by his sacrifice. The thought of the coming Kingdom was the power of God to help the Lord Jesus through the hour of trial, and so will it be with all his brethren. 'Fear not, little flock', he said, 'it is your Father's good pleasure to give you the Kingdom.'"