Do you really understand what all of that entails, all the grief and the sorrow and the pain, the agony of what He was going through? Do you really, really understand what it takes to sit on the right and the left side of Jesus? How do you get to that position?
This is why He asked John and James, can you do this? If you want to be a true leader in the church or in the Kingdom of God, are you willing to take it this far? "Oh yeah, we can do it. Let's go." Stupid men. Jesus is the ultimate example in each category: leadership or high position, service, and sacrifice. It does not get any better than Him in all three of those categories. And the instruction for His disciples is that godly leadership is shown in sacrificial service to others. I think we understand that general principle.