Matthew 4:17 ->
From that time, Jesus began to preach, saying, "Repent, for the Kingdom of Heaven is at hand."
As he walked by the Sea of Galilee, he saw two brothers, Simon who is called 'Peter' and Andrew his brother, casting a net into the sea; for they were fishermen. He said to them, "Follow me and I will make you fishers of men."
Immediately they left their nets and followed him.
And going on from there he saw two other brothers, James the son of Zebedee and John his brother, in the boat with Zebedee their father, mending their nets, and he called them.
Immediately they left the boat and their father, and followed him.
He went about all Galilee, teaching in their synagogues and preaching the gospel of the Kingdom, healing every disease and every infirmity among the people.
So his fame spread throughout all Syria; and they brought him all the sick, those afflicted with various diseases and pains, demoniacs, epileptics, and paralytics; and he healed them. Great crowds followed him from Galilee and the Decapolis and Jerusalem and Judea and from beyond the Jordan.
I've skipped some interesting and important material -- which does imply certain things about what this Kingdom of Heaven means -- because this is the first place here it's mentioned explicitly. Jesus has resisted the Devil's suggestions that he command miracles and put himself in charge of that Kingdom, whether by spectacular shows of divine favor or by any of the ways that secular rulers acquire power. This is to be 'The Kingdom of God,', not 'The Kingdom of Jesus.' His colleague John has been arrested by Herod Antipas, and everyone knows how that will most likely turn out -- but Jesus takes up John's mission and raises the ante: "The Kingdom of Heaven is at hand!"
Clearly Jesus is an impressive man; but it isn't his personal power he's relying on when he chooses certain people to drop everything and follow him; and they do it. He doesn't invite Zebedee, who is sitting in the boat with his sons; and is probably a good, competent man. It isn't his personal power that cures all these ailing people.
If the Kingdom of God is taking form, then God is beginning to actively reign. And that means miracles happen. We don't need to explain this by modern psychosomatic medicine or diagnoses of 'why can he cure that ailment?' We do need to drop our modern assumption that The Laws of Nature Must Be Enforced!
Both John and Jesus have been calling on people to 'repent'. That's an interesting word, which didn't mean merely cleaning up their act. I'm told it meant literally to change direction and orientation, or (for the Greek word) to 'go beyond the mind that you have.' God is resuming visible rule of this world; and if you don't change your outlook you aren't going to like it.