Kings and queens typically live very lavishly, benefiting from all the work of their subjects. This can lead to many temptations, especially as royalty think more of themselves than the people they are supposed to serve.
St. Casimir of Poland was a different king than most, as he did what he could to serve his people. He knew the temptations of leading a comfortable life and made many sacrifices to remind himself of his duties.
According to a biography written 36 years after his death, he inflicted many penances upon himself to be as uncomfortable as he could.
He consecrated the flower of his age to the exercises of devotion and penance, and had a horror of that softness and magnificence which reign in courts His clothes were very plain, and under them he wore a hair shirt. His bed was frequently the ground, and he spent a considerable part of the night in prayer and meditation, chiefly on the passion of our Saviour.
Prayer was a hallmark of his life and he made sure to participate in the prayers of the Church whenever he was able.
He often went out in the night to pray before the church-doors; and in the morning waited before them till they were opened to assist at matins. By living always under a sense of the divine presence he remained perpetually united to, and absorbed in, his Creator, maintained an uninterrupted cheerfulness of temper, and was mild and affable to all. He respected the least ceremonies of the church: everything that tended to promote piety was dear to him.
St. Casimir also had a special love of the poor and had compassion upon them, doing what he could to alleviate their suffering.
St. Casimir remains a powerful example to all leaders in the world, showing them how to use their position wisely.