A friend of mine used to give this answer when he was asked why he was a missionary: "Because I am convinced it is saving my life."

There are many things that promise to renew or give us life. Energy drinks, diet plans, nutritional supplements, health clubs and exercise equipment are among the products and programs that promise to upgrade our energy, vitality and enthusiasm. Of course, when we think about transforming our lives, we might want to start with turning to God.

In today's Gospel reading, Jesus tells his followers: "I am the living bread that came down from heaven; whoever eats this bread will live forever…. Amen, amen, I say to you, unless you eat the flesh of the Son of Man and drink his blood, you do not have life within you."

I think a lot about the first part of this message --- that Jesus is the bread of life and the source of eternal life. I don't often think about the second part --- that if I do not practice my faith and rely on him, my life will slip away.

I rarely feel this kind of urgency about practicing my faith. I mean, I know I should be more consistent in my worship, prayer, community and service. But I rarely feel that it's a matter of life or death. The closest I come to a sense of urgency about my faith is when I'm facing some kind of crisis --- when a relationship, or a job, or my health is at risk. But then I pray for the crisis to end more than I pray simply to strengthen my faith.

Of course, the most obvious way we can feed on the flesh and blood of Christ, the bread of life, is through our Eucharistic celebrations. In our country, we have so many of these available to us that it's easy to take for granted that the bread of life is here for us. We have our choice of daily and Sunday Masses, and we usually have ministers who will bring us the Eucharist if we are shut in or otherwise unable to attend Mass.

Our celebrations would probably take on a much more vibrant tone if we approached them as if our lives depended on being there. Unless we eat the flesh of Christ, and drink his blood, we will not have life within us. Perhaps the reason so many of us feel so spiritually weak and tired is that we are not availing ourselves of the nourishment God offers. For the Bread of Life is not just present in the Eucharist, but also in prayer, Scripture, and community.

While we may be well served by joining a gym, improving our diet, and tending to our physical health, life means much more than our physical condition. Jesus reminds us that the only real elixir that can deliver on the promise of total transformation is the bread of life. If we feel our lives slipping away, we might start there for real change.

Bill Peatman writes from Napa.