For the listeners of Jesus it was evident that the vineyard was the chosen nation (Israel). The work in this vineyard is commanding.
For us it is also evident that the vineyard is the church. This is visible because we are visible but also invisible. We can therefore say the church provides a space for a love for God and for man, and also for feelings and relationships.
The gospel presents us with two sons invited to work in the vineyard.
The first said, I will not go, but changed his mind and went. The other, responsible for the invitation, did not go. The gospel tells us what was happening in the heart and mind of the son who had not fulfilled his fathers' request. But something must have happened that changed his mind. Maybe he had more enjoyable things to do, or maybe he was just lazy, or perhaps he was full of cynicism.
The first son we know more about. Something changed his reluctance. He needed time to think through his decisions.
Even today, we also need time to look at the decisions in life. Today, Jesus wants to show us there is no model personality. Life is not ideal, and our motivations and actions are often complicated.
It is important once we give our word to God. Our whole life is in fact based on the words of God's fulfillment. The Christian life, starting with Baptism involves promises to be fulfilled. Perfecting our Christian life takes place each time by implementing the word of God.
No matter how many times we respond to God's invitation negatively with promises and expressions of our willingness...the most important is how many times we are able to repent and how many times we respond to God's invitations.