Luke 22:44 "And being in an agony he prayed more earnestly: and his sweat was as it were great drops of blood falling down to the ground."
It is interesting that Luke is the only one of the gospel writers to mention that Jesus' sweat was as great drops of blood. This is probably because Luke was a physician (Col. 4:14), and therefore, this had special significance to him.
There have been documented cases of people actually sweating drops of blood under extreme emotional pressure. This might explain why Luke is the only writer to mention the angel strengthening Jesus. Just as when Jesus encountered Satan during His forty days of fasting and temptation in the wilderness and the angels ministered unto Him (Mk. 1:13), so here, He needed supernatural strength to endure His sufferings.
The use of the words "as it were" might also mean that the sweat of Jesus was only comparable to blood in consistency or size, but it certainly underscores the effect Jesus' agony had on His physical body.
Jesus' sufferings for us were more than just physical. In the garden, before He suffered physically, He suffered emotionally, almost to the point of death. As Luke records, an angel had to come and give Him strength or the emotional struggle alone would have killed Him.
All that Jesus did was motivated solely by love. It was for the joy that was set before Him that He endured going to the cross. He didn't do what He did to save us out of pity or a sense of obligation as our Creator. He did it because He loves us.