That is the little-understood truth that whenever we obey God, in the minutest of matters, though nothing seems to have changed outwardly in our circumstances as a result, the reality is that something has occurred in the invisible world. In the flesh, you may still be sitting in the kitchen chatting with a group of people over dinner, just as you were in the seconds before you committed the obedient act (say, you stifled an urge to make a retaliative comment). But in actuality a slight change has been made in your soul. You have just become stronger and more like Jesus in some hard-to-quantify way. And those who have done that spiritual warfare and died that little death can feel the change in themselves. They have just become by one small degree further transformed into the image of Christ (2 Corinthians 3:18).
Likewise, if you decided to slouch and just let your mouth spout out whatever worthless word comes into your head, you do not see a difference in the physical dimensions a moment afterward: You are still sitting with your family or friends at a table; they are still passing the plate of sandwiches around. But in the spiritual domain, you have forfeited an opportunity to become more like Christ, and there is an intangible but real consequence in your soul.