Jesus forbids his disciples to lay up treasure on earth. But what's the alternative?

Jesus tells his disciples that they must not lay up treasures on earth. Why do people want earthly wealth? And do Jesus's disciples have anything better?

The Lord Jesus took it for granted that his disciples would fast. Why? What should be our motive? What can fasting achieve?

Jesus tells us that when we pray we must be aware of the reality of evil, we must know that it threatens us, and we must pray for our Father to deliver us.