Having left the full-time rabbinate more than two decades ago, his days are largely spent writing and lecturing -- or as he put it recently, doing the rabbi stuff he enjoys and leaving the rest to others.
"I feel very blessed," said Kushner, who received the Jewish Book Council's Lifetime Achievement Award this month.
But the author of more than a half-dozen books, several of them best sellers, is not without regrets -- a topic he addresses in his most recent book, "Overcoming Life's Disappointments," published in 2006.
Asked about his own misfortunes, Kushner cited his son's early death and having the woman he wanted to marry choose someone else. He also recalled losing out on the pulpit of a larger congregation.
Kushner told a story about a Protestant minister who spent his career waiting for his colleagues to die or be caught in a scandal so he could take over their church. The minister had grown to resent his congregants, whom he saw as emblematic of his own failure to move up in the world.
"That was an eye-opening story for me because I saw a certain amount of myself in that," Kushner said. "Maybe without the jealousy, without wishing ill to my colleagues, because I was happy where I was. But there was a sense that I didn't really appreciate the people here. I've come to appreciate them more, to be much more sensitive to the things that hurt them."
Sensitivity to the hardships of others is a hallmark of Kushner's writing, which first gained acclaim after the publication of his second and best-known book, "When Bad Things Happen to Good People." He has gone on to author more than a half-dozen other books, several of them best sellers, and was an editor of the Conservative movement's 2001 Etz Hayim Torah commentary. In 1999 he was named clergyman of the year, and in 2004 he read from the book of Isaiah at the state funeral of Ronald Reagan.
Long popular in Christian circles, Kushner has been seen as more of a mixed blessing among more traditional Jews.
He says he gets a better reception from Mormons than from Orthodox Jews, and it's not hard to see why. Kushner sees the world through the prism of human needs, and if that means taking liberties with Jewish theology to make people feel better, he's more than willing.
"I always thought Judaism was at its best when it not only looked at text, but when it looked at people," he said.
Kushner committed his gravest offense, as the Orthodox see it, in "When Bad Things Happen to Good People." He labored to reconcile the twin Jewish beliefs in God's omnipotence and his benevolence with the reality of human suffering, ultimately sacrificing the former to salvage the latter.
Kushner's God is limited in his ability to control the random hazards of life that result in tragedy on a widespread and a smaller scale, like the Holocaust and the death of a child.
It is a view that runs afoul of traditional Jewish teaching about God.
Remarkably, Kushner himself concedes the point, acknowledging that he may be wrong about God. But he maintains that his writing has helped restore faith, return people to prayer and permit them to heal.
"I don't know if I'm correct theologically. I don't know the reality of God," Kushner said. "What I do know is my book makes people feel better. It gives them back the ability to go to shul or to church and pray and to believe in God, to believe that God is on their side. It restores to them the legitimacy of outrage when something tragic has happened to them."
Kushner was born in Brooklyn and educated in the New York borough's public schools. After his ordination at the Jewish Theological Seminary in 1960, he went to court to have his military exemption waived.
For two years he served as a military chaplain in Oklahoma before assuming his first pulpit, as an assistant rabbi at another Temple Israel, this one in Great Neck, N.Y.
Four years later he came to Natick, where he has remained. In 1983, with his book a best seller and demanding more of his time, Kushner cut back to part-time at the synagogue. Seven years later he stepped down to devote himself fully to writing.
The congregation, believing their then-55-year-old rabbi too young to be named rabbi emeritus, made Kushner its rabbi laureate, a title held by only a handful of American spiritual leaders.
Last month, Kushner turned his human-centered approach to the challenges facing the Conservative movement in an article, "Conservative Judaism in an Age of Democracy," published in Conservative Judaism magazine. In the article, Kushner argues that in an era of personal autonomy, Jews must be given positive reasons to choose observance.
Conservative Judaism has withered, in part, because it still treats mitzvot as commandments, Kushner said. Instead, it should market itself as the movement that satisfies the deep human need for community and purpose.
"My seminary training was all about Jewish answers. My congregational experience has been more in terms of Jewish questions," Kushner said. "I start with the anguish, the uncertainty, the lack of fulfillment I find in the lives of the very nice, decent people who are in this synagogue and who are my readers. And Judaism is the answer."
"How do I live a fulfilling life is the question," he said. "And Judaism is the answer."