Dietrich Bonhoeffer said Christianity without discipleship was not Christianity at all. Discipleship is not something to be admired in the super-spiritual, it is a requirement for every follower of Jesus. If Jesus is your Lord, you will be His disciple. You don’t find so-called “casual Christians” in places like Afghanistan, Iran, China, and so many other countries around the world.
They understand following Jesus is a call to discipleship. It is a call to die to yourself and live for Christ. If you are serious about serving God, you will spend your days learning to become His disciple. The spoils of this world will hold no appeal for you. There will be Jesus and nothing else.