For the next 28 or so years of Jesus' life, nothing is recorded about Him in the Bible (with the exception of Him being 12 and talking to the priests in the Temple).
Matthew three opens with John the Baptizer (the child who leaped in Elizabeth's womb when Mary, her cousin, went to visit her when she was pregnant with Jesus in Luke 1), preaching to the world to repent. This is a fulfillment of of Isaiah's prophecy in the OT. John is described as quite the interesting fellow (verse 4).
John's purpose was to tell people about the kingdom of God, so they would repent and be baptized.
At this point, new players enter the scene - the Sadducees, who didn't believe in resurrection, and the Pharisees who were devout religious people who followed the letter of the Law (the Torah) but not the spirit of it (so to speak). Jesus consistently called them "hypocrites." They came to be baptized because it was the popular thing to do, not because they genuinely wanted to change their lives.
John says, "It's your life that must change, not your skin!"
That line in itself leaves me enough to think about for today!
However, Jesus enters the scene, and there is always time for Him. He came to John the Baptizer to be baptized. John, as you can imagine, feels unworthy. Jesus then reminds John of what the OT has been teaching and pointing toward - this moment. The start of Jesus' ministry.
When Jesus comes up from the water, we see a beautiful picture of the Trinity - God the Father as a voice from Heaven, God the Spirit descending like a dove, and God the Son standing in the water next to John.
God chose Mary. God chose Joseph. God chose John. God chose Jesus.
And, God chose you.