Jesus sends his disciples out to preach about the kingdom of God and to heal the sick with the power & authority He has given to them (v.1). And these are the instructions he gives them... "take nothing for the journey-no staff, no bag, no bread, no money, no extra tunic." "Take nothing." Notice Jesus doesn't only tell them to take nothing, he's specific. He Jesus covers any future questions they might have had about these instructions. For example, maybe Matthew could have said, "but we have to eat so we can have energy to serve shouldn't we at least bring some food?" or say Andrew was thinking, "shouldn't we bring an extra tunic so we don't offend people with the smell of our dirty one?" No, no, no. He answered every possible question.
What was the journey they were on? Their journey was to do the work of evangelists. Their journey was to be Christ to others, to teach others the truth Christ had taught to them, to give others the hope Christ gave them, to love others with the patient and accepting love of Christ. To live our lives like Jesus we don't need the material things of this world. To live like Jesus we just need Jesus.