In his daily homily, Pope Francis spoke of St. John's Gospel reading about the prayerful perseverance of the young man who waited 38 years at the pool of Bethesda to be healed. He compared him to many Christians who live in a state of laziness and are “incapable of doing anything except complain about everything.”
Sloth is a poison. It's a fog that surrounds the soul and keeps it from living. It's also a drug, because if you try it too often, you start to like it. You end up being “addicted to sadness,” “addicted to sloth.” It's like air. This is a sin found commonly enough among us.
The pope explained that “this is a sin the devil can use to annihilate our spiritual lives and our lives as people.”