“On September 10, 1946, a day that is now celebrated annually by the Missionaries of Charity as Inspiration Day, while traveling to Darjeeling on a dusty, noisy train, Mother Teresa experienced another call,” wrote Meg Greene in Mother Teresa: A Biography, “The message was quite clear: I was to leave the convent and help the poor while living among them.”

Although in the years that followed, she would have little to say about Inspiration Day, she referred to it as “the call within the call.” Mother Teresa spent most of her life in India, but she had been born in Albania in 1910. She became a Catholic nun and joined the Loreto Sisters in Dublin Ireland in 1928. It was the Loreto Sisters who sent Teresa to train as a novitiate in Darjeeling, India, where her calling revealed itself. Mother Teresa’s example reminds us that the calling that can inform a life mission often comes after years of preparing ourselves to receive it.

She founded the Missionaries of Charity, which would become a congregation serving “the poorest of the poor” in Calcutta’s slums. “Mother Teresa struggled with a draft of the order’s constitution,” wrote Greene. The nuns would take vows of chastity, poverty, and obedience. “To these she added a fourth vow: ‘to give wholehearted and free service to the poorest of the poor.’” The order grew over the next five decades to operate in more than 100 countries with over 4,000 nuns managing homes for those dying from HIV/AIDS, leprosy, and tuberculosis, as well as running, orphanages, schools, and soup kitchens.

In 1979 Mother Teresa was awarded the Nobel Peace Prize in recognition of her humanitarian work. Despite the prestige of this international award and the global scope of the order she founded, her accomplishments demonstrate that even a small mission matters and can grow over time into a much larger one. She famously said, “If you can’t feed a hundred people, then feed just one.”