Blessing is the projection of good into the life of another. It isn't just words. It's the actual putting forth of your will for the good of another person. It always involves God, because when you will the good of another person, you realize only God is capable of bringing that. So we naturally say, "God bless you."
You can bless someone when you will their good under the invocation of God. You invoke God on their behalf to support the good that you will for them. This is the nature of blessing. It is what we are to receive from God and then give to another.
Now we need to deepen that just a little bit, because it isn't just a verbal performance. It isn't "bless you" said through gritted teeth. It's a generous outpouring of our whole being into blessing the other person. So, among other things, you don't want to hurry a blessing. It becomes a habit that we say thoughtlessly, "God bless." Well, that's better than a lot of other things we could say, but we want to be able to put our whole self into our blessing. That is something we need to be thoughtful about. We don't just rattle off a blessing. It's a profoundly personal and powerful act.
In Numbers 6:24–26, we find the great Aaronic blessing. This is the blessing Moses instructed his brother, Aaron, to place on the people of Israel. Thank God for it! When you try to improve on it, you realize you are not going to make much headway.
"The Lord bless you." That means "God bring good consistently into your life." "The Lord bless you and keep you." That means "God protect you. God build around you his safekeeping. The blood of Jesus and the Spirit of Christ be ...