This statement confirms the message of Jesus regarding worldly possessions: Material things do not satisfy us because we are spiritual in composition. We are not these physical bodies: Rather, these physical bodies are temporary vehicles - and therefore earthly possessions do not satisfy us.
Otherwise, Jesus would have advised his students to be careful about their bodies, right? If we - and Jesus' students were physical bodies, why would Jesus tell them not to worry - from the Greek word μεριμνάω (merimnaō) - about their bodies? Furthermore, if his students were the physical body, then surely he would have advised them to take great care regarding the food put into the body.
Yet Jesus is clearly instructing his students not to worry about their physical bodies - including the food given to their body and the clothes that cover the physical body.
Why? Because these physical bodies are temporary. They will live no more than a few decades and then they will get sick and die. After that, they will decompose and turn into soil.
Rather, Jesus was concerned about their spiritual welfare. He wanted them to focus their lives on the Supreme Being. He wanted them to come to know and love and serve the Supreme Being with all their hearts.
Jesus confirms this with the statement previous to this:
"This is how it will be with whoever stores up things for themselves but is not rich toward God." (Luke 12:21)Jesus is confirming that focusing one's life on the physical world - including the accumulation of possessions - is useless. Those of us who focus our lives on the names and forms of the physical world without developing our relationship with the Supreme Being will be left with nothing at the end of our physical lifetimes.
All our material possessions will be lost when our body dies
That's right. When our body dies, all of our physical possessions - including wealth, property, fame, reputation and family - will all disappear at the time of death. They might still exist after our bodies die: But they won't exist as far as we are concerned. They will be picked over by others and will also eventually decompose just as our bodies will.
What changes at the time of death? The physical body is still there - lying motionless. There is no chemical difference between the living physical body and the dead physical body. The difference is that the living being - the spirit-person who resided within the physical body when it was alive - is gone. The spirit-person within (each of us) leaves the body at the time of death.
This is why people report seeing their bodies from above in clinical death cases. They can see their body from above because they left their body at the time of (clinical) death.
What do we keep when our bodies die?
So what will we be left with when we leave behind the physical body at the time of death? Only our relationship with the Supreme Being.
This is why Jesus stated:
“My food is to do the will of Him who sent me and to finish His work." (John 4:34)Jesus isn't concerned about the physical body and what it will be fed. His concern is his loving relationship with the Supreme Being. Jesus wants to please the Supreme Being - who sent him here to invite us to return to our home in the spiritual realm.
This is because the Supreme Being loves us, and He wants us to be happy. So He sent Jesus to invite us home.
But misidentifying ourselves as the physical body is the biggest barrier to accepting that invitation. Most of us think that we are the physical body we are occupying. We identify ourselves with our physical name, our hair color, our eye color, fingerprints, DNA, body shape and so on. Yet all of these characteristics are temporary. They do not last. And they have nothing to do with our spirit self - our inner person - the child of God.
It is for this reason that Jesus is trying to clarify the temporary nature of the physical body - compared to the eternal nature of our relationship with the Supreme Being.
This is also why Jesus stated:
"Do not work for food that spoils, but for food that endures to eternal life, which the Son of Man will give you." (John 6:27)"Food that spoils" is the food of the physical world - which may feed the physical body. But such "food that spoils" is not fulfilling. It feeds the machine we call the body. But doesn't feed the spirit self within. So it is not fulfilling.
What is the "food that endures to eternal life which the Son of Man will give you"?
This is love for the Supreme Being and all His children, and the loving service that expresses that love.
Jesus is introducing his students to God and guiding them in the process of re-developing their loving service relationship with the Supreme Being. Jesus confirmed this overall intent of his teachings when he instructed them:
" 'Love the Lord your God with all your heart and with all your soul and with all your mind.' This is the first and greatest commandment." (Matt 22: 37-38)