To love means to serve the object of your affection without reservation. That is the message Jesus conveys to James and John. And this scene is beautifully depicted against the fact that Jesus has just spoken of His coming Passion and Death. Knowing what awaited Him, Jesus choose to go to His Cross. He did not, put conditions to His service and love of humanity, gave Himself completely for it.
The Cross awaits all of us who wish to love truly and completely. But it is not a negative, it is the grace to form us into God’s Image. The suffering will be there, but in the temporary sense, it will be more like a discomfort. But Peace will pervade your life.