Do not give to those who will just return the favor, but rather to those who cannot repay you.
What Jesus is talking about is the lost art of gracious living. Lost to many of us, at least, and to most of us at least some of the time.
If we live our lives with the attitude that we deserve nothing, then everything that we receive is gift, and gratitude is the result.
And if we live our lives generously, giving to those who cannot repay, graciousness is the consequence. In both the giving and the receiving, grace abounds and gratitude rules the day.
Two gift giving moments come to mind. The first occurred a number of years ago as my siblings and I were gathered at my folks home for Christmas. We were still in the practice of exchanging gifts with one another. But none of us were particularly adept at making those purchases in advance. Thank God, for "Land's End". It was comical. We basically passed the Land's End catalog around and each ordered something for the others. 2 day delivery insured a timely Christmas celebration.
The second celebration was with our own children. They had expressed a desire to move toward a 'grown up Christmas', with less emphasis on the gift exchange. I couldn't quite let go of the gift giving tradition of Christmas, but had the inspiration to use the Evangelical Lutheran Church in America's "Good Gift" program. For each of our children, we offered a gift, not too them, but in honor of them. Farm animals for third world families. A doctors visit and vaccinations for the less fortunate. Water purification tablets. School supplies. Each chosen because we thought it appropriate for that child, based on their interests. Giving such gifts simply felt better.
More difficult, though, is this matter of sitting back and receiving as gift from others. Particularly, when you simply cannot repay. It's a humbling experience. Perhaps a better word would be humiliating. And yet to be touched by the graciousness of others, and to be in a situation in which the only possible response is to say 'Thank you' is good for the soul.
The importance of such exercises is that life itself, is grace based. The very breath of life that sustains us is a gift. Birth is a gift. Everything is a gift. And the more we come to appreciate this giftedness of all life, the richer we become spiritually.