Jesus responds to their request by saying that it was now time for Him to be glorified. They did not understand that He was referring to His death and resurrection. The grain of wheat that had to die was Jesus. Once a seed has sufficient moisture and temperature, it will split and a new plant starts to grow. The new plant takes everything from the seed to accomplish its growth. In other words, the seed gives itself up (dies) for the new plant. With proper care, the new plant will produce much fruit of its own kind. Jesus knew from before the foundation of the world, that His mission would be to give Himself up for us. When Jesus freely gives Himself up and is buried, the germination process has begun. Now all who accept Him are new creatures. Formed completely out of His body from His own nature. Now that the process of growth has started, we must continue that process by caring for the new creature. We do that by studying Scripture, meditating on His Word and communicating with God through the Holy Spirit. If we follow the example of Jesus, we become bond slaves to Him and servants to our fellow man. We keep this up until our physical body is used up or until Jesus returns, whichever comes first.
17 If anyone belongs to Christ, there is a new creation. The old things have gone; everything is made new! –2 Cor. 15:17 (NCV)
Then when Jesus returns, the transformation will be complete! We will have new bodies because our fleshly bodies cannot stand in the glory of God.
46 The spiritual did not come first, but the physical and then the spiritual. 47 The first man came from the dust of the earth. The second man came from heaven. 48 People who belong to the earth are like the first man of earth. But those people who belong to heaven are like the man of heaven. 49 Just as we were made like the man of earth, so we will also be made like the man of heaven.—1 Cor 15:46-49 (NCV)