The word train in that verse means, “to narrow in” or “to hedge in” or “to limit.” This is what we do as parents—we don’t give our children every option. We limit their choices. God, as the perfect Father, hedges us in. He puts a hedge on either side of us to help direct our course. Jesus even calls this way of life “the narrow way.” We can begin to see that God limits us by narrowing our options. We still have free will, and we must still make the choices, but because of the hedge that God provides, we don’t have as many options as we otherwise might if we were still in this world.
In Deuteronomy 30:15-19, God says that He sets before us life and death, blessing and cursing, and so on. God sets the options before us, and we choose. The options in this case are very broad and far-reaching. On one hand, there is life, good, and blessing; on the other hand, there is death, evil, and cursing. God even counsels us which choice to make—but He leaves the choice to us.
That passage in Deuteronomy 30 links obedience to God’s laws and instructions with choosing life and blessing. “Choosing life” is not a decision that one makes at a single point in time, such as baptism, but rather it is the overall direction and approach, as well as the specific decisions we make at each turn. It is a continual choice.