This is Matthews'a account of Jesus' walking on the water as the disciples struggle in a terrific storm and night on the Sea of Galilee. The incident bridges the events of Jesus' having fed the 5,000+ and the increasingly open hostility to His ministry by the Jewish leadership afterward.
The number one obstacle to one's spiritual growth is yourself. That is putting yourself first and living a self-centered life short-circuits your spiritual growth faster than anything. Listen to what Jesus says about that.
Jesus being the perfect communicator, wants his followers to know what it means to be a disciple of his. There are several clear characteristics of what it means to be a disciple of Jesus Christ.