The Oil Of Gladness is the Holy Spirit of gladness. When you are filled with the Holy Spirit you experience His Spirit Fruit of joy.
A Spirit Filled believer should be joyful. Whenever you see a believer who has a defeated, bitter, or stern demeanor be aware that the Holy Spirit is not in the dominant position in their life.
Our Lord made some very strong statements but His heart is about faith and freedom which exclude the bondage of burdens of any type. He was able to attract large crowds because He was covered and filled with the Oil Of Gladness, His Holy Spirit.