Jesus is speaking about the baptism of his coming suffering. And he is very much distressed about it. Jesus is going to suffer to such an extent that he is highly distressed before it ever happens.
When we take the Lords Supper, we would do well to try to appreciate the extent of Jesus’ distress and suffering. He suffered for us-in our place. But how much did he suffer? Enough to be very much distressed before the fact.
We should remember that Jesus suffered - for us - and painfully so. This will help us realize the evil of our sin and more appreciate our salvation from sin.