Two divergent views
Paul tells us about his "secret" death in the passage before us today. In the main, there are two divergent views on this passage. One view is that Paul is referring here to the teaching he expounded in Romans 6 -- that when Christ died at Calvary, we all "died" in Him, but because He came back from the dead we must now apply ourselves to appropriating that resurrection power and allow it to work in us to overcome self and sin. They say Paul's statement about being "crucified with Christ" has reference to that. Others take the view that Paul is referring to a specific experience in his life, following his conversion, when his "old man" (the carnal nature) "died" to self-interest and self-concern. Thus, the "old man" being crucified, the Christ-man rises in his stead.
Personally I see truth in both these views. Sanctification is a process but it can also be a crisis. Many Christians can testify, as did George Muller, that even though they were applying the sanctifying power of the Holy Spirit in their lives day by day, there came a moment or a period when they experienced a critical putting to death of the ego. Not everyone, it seems, is brought by the Spirit to experience sanctification as a crisis, but it is significant that most of the saints whose lives are marked by a high degree of holiness testify to such an experience. Let your heart be open to God on this matter today and listen to what He might say to you. Perhaps this could be the day on which you die a "secret death."
My Father and my God, I choose what You choose. If today You choose to lead me into a deeper understanding of how to "die" to my self-interest, then I choose to follow. Guide me, my Father. In Jesus' Name. Amen.