Father Sullivan’s source of his power of succouring the afflicted was his deeply spiritual life, love of prayer and detachment from wordly comforts.
Any of his religious brothers can attest to the fact that every day he spent long periods, often many hours, before the Blessed Sacrament, as well as a great part of every night. One night in January of 1925, the plumber at Clongowes College was working late in the chapel repairing hot pipes. When he entered the chapel at 11 p.m., he found Father Sullivan kneeling on the marble steps before the altar. At 2 a.m., the work was finished and the plumber left, but Father Sullivan was still there praying. He was also known to spend hours at the community cemetery, being greatly devoted to the Holy Souls in Purgatory.
Father Sullivan allowed himself only an incredibly small amount of sleep. A servant who looked after his room for about a year noticed that the bed was used only about every second night, sometimes looking as if Father had merely lain down on it without covering himself with the bedclothes.
Father always recited his breviary (daily prayers said by priests) kneeling in the chapel, often near an open window, apparently oblivious of the cold. He had no overcoat, only a worn and faded waterproof coat, and he was never known to wear an umbrella or wear gloves. Through love of poverty, he wore his clothes until they were patched beyond description, though always neat and clean.
His boots were old and much patched, and it seems he managed to do with one pair only. Sir William, Father Sullivan’s brother, once noticed the bad state of Father’s boots and sent him a new pair, who wrapped them up in brown paper and went off down to the docks to give them to someone needy. Some time later, Sir William asked him whether the boots fitted. “Perfectly,”replied Father John. During a retreat at a convent, a lay-sister noticed that inside his boots was “a handful of small pebbles”.