H/T: The Way of the Cross, Ray C. Stedman (here)
…Peter denied that he had any connection with Jesus, said he did not know him, and affirmed his disavowal with oaths and curses. Thus he denied his Lord. This is exactly the word Jesus chooses when he tells us that, if we are going to come after him, we must first deny ourselves.
It is important also to understand that he does not mean what we usually mean by “self-denial.” By this we usually mean that we are giving up something. Many people feel it is only right to deny themselves something during Lent, to give up various bad habits, like wearing overshoes in bed. But Jesus is not talking about this kind of “self-denial.” He is never concerned about what we do so much as with what we are. Therefore he is not talking about giving up luxuries, or even necessities, but about denying self, which is entirely different.
Denying self means that we repudiate our natural feelings about ourselves, i.e., our right to ourselves, our right to run our own lives. We are to deny that we own ourselves. We do not have the final right to decide what we are going to do, or where we are going to go. When it is stated in those terms, people sense immediately that Jesus is saying something very fundamental. It strikes right at the heart of our very existence, because the one thing that we, as human beings, value and covet and protect above anything else is the right to make ultimate decisions for ourselves. We refuse to be under anything or anybody, but reserve the right to make the final decisions of our lives. This is what Jesus is talking about. He is not talking about giving up this or that, but about giving up our selves…