A colleague asked me recently, “What sustains you in your vocation?” That’s a great question. It deserves reflection from all of us.

John Calvin believed that it is the vocation itself, the fact of having been called by God which sustains us. That’s a great response, and I’m sure it is true. But, in the day-to-day slog and grind of living our vocations, beyond the assurance that we are where God called us (which is no small thing!), are there other things that sustain us? Prayer, regular Bible study, worship, the practice of Sabbath?

A physician, who I admire greatly, told me that he has found deep satisfaction and new energy for his vocation because of a major breakthrough in the treatment of a disease he has spent most of his life fighting. That is certainly sustaining, knowing that what you do matters, that it makes a real difference in the lives of others.

Research has found that professional burnout is often related to the feeling of futility, and is not simply a symptom of hard work or long hours. Burnout might, according to this research, be more closely related to depression than merely to weariness.

Amid the relentless pace of life, of families and work, running and rushing as we do, in the midst of a culture addicted to the ephemeral and resistant to the enduring, it is crucial to believe that our efforts ultimately are not futile, that the God who (as the Psalmist tells us) collects even our tears in a bottle, the God who (as Jesus tells us) numbers even the hairs on our heads, cherishes and remembers the lives we live and the work we do.

In light of that, what sustains me most, probably, is friendship.

When I use the word friend, my perspective is influenced by Diana Fritz Cates’ marvelous study, “Choosing to Feel: Virtue, Friendship, and Compassion for Friends,” in which she explores the meaning of friendship in Aristotle and Thomas Aquinas, both of whom believed that “my friend is ‘another myself.’” And also by Seneca, Marcus Aurelius and Epictetus, who, like all the Stoics, took friendship very seriously.

Seneca, for example, wrote about friendship as a matter of life and death:

“For what purpose, then, do I make another my friend?...In order to have someone for whom I may die, whom I may follow into exile, against whose death I may stake my own life, and pay the pledge too.”

Friendship, for Jesus, was also a matter of life and death. “No one has greater love than this, to lay down one’s life for one’s friends.” Jesus also makes it clear that friendship is predicated on something deeper than pleasure and mutual advantage (John 15: 13-15):

“You are my friends if you do what I command you. I do not call you servants any longer, because the servant does not know what the master is doing; but I have called you friends, because I have made known to you everything that I have heard from my Father.”

I place all of this in the balance against a trend that has devalued the idea of friendship to such a point that a person can say with evident pride (and without the least shred of irony), “I have over five hundred friends on Facebook!” Now, admittedly, my standards for friendship may be high, but no, they don’t have five hundred friends, not even virtual friends.

The reason friendship sustains us, like nothing else, is because friends together are always more than the sum of their parts. Their strengths combine, and they more than compensate for one another’s weaknesses, making one another stronger through the gift of mutual correction and forbearance.

David Wood, a pastor and former associate director of the Louisville Institute here at Louisville Seminary, acknowledges four specific capacities of friendship, each of which contributes to sustaining ministry. He says that friendship helps us to cultivate knowledge of God (in contrast to the tendency to elevate solitude at the expense of community in matters of spirituality). Friendship cultivates our knowledge of ourselves. Friendship gives us an appropriate sense of intimacy, making us more capable of ministering to congregants not out of our own neediness, but out of our fullness. And, friendship cultivates “a capacity to deal with conflict.” He writes, “If we are to be capable of not taking everything personally, there must be someone with whom we can share our lives personally, without fear.”

I leave you with the same question, “What sustains you in your vocation?”

Michael Jinkins is president and professor of theology at Louisville Presbyterian Theological Seminary.