Interestingly, in these three verses Paul employs forms of the same Greek word, lambano (lam-ban'-o) and katalambano (kat-al-am-ban'-o), to construct an ancient word play on the concepts of attained, apprehended, lay hold, and laid hold. The NKJV translators did an excellent job in conveying that syntax in English, so that these verses read with a kind of a tongue-in-cheek lilt to them, demonstrating the apostle's underlying, almost playful, attitude in refuting any anticipated feedback from his contemporary, or future, audiences that might accuse him of being conceited.
Has that, or something similar, happened to you? Has someone disparaged you because of your being freed from the penalty of sin in Christ? It usually takes the form of, "Oh, those Christians! They think they are so much better than everyone else!" Or, "They're just thrilled that everyone else is going to Hell, and they're not!" For a well-taught Christian to feel superior because his sins have been forgiven on the Cross is completely illogical. After all, it means our sins were so bad that God had to send His Son to die in payment for them. Nothing at all about ourselves to boast about in that. And again, for a well-taught Christian to be joyful over someone else's damnation, even their most vile and debauched enemy, means that he or she does not understand their own depravity before a holy God.
The Bible warns explicitly against a follower of Jesus becoming puffed up. We have done nothing to either earn, or maintain, our salvation. Even the faith that we exercise in becoming saved is a gracious gift from God, as is everything good that we have received. It makes no sense to crow about a gift as if you did something to earn it. A gift is just that, a gift. Otherwise, it's wages or a trophy, and not a gift. In truth, a gift says more about the quality of the giver than the recipient. So, a puffed up, conceited Christian is an oxymoron; simple as that.
But people don't always behave logically, or truthfully, and Paul's contemporaries were often as idiotic or manipulative as we are today, so he explains his attitude as being one of knowing that he is far from having fully attained the righteousness that is his through faith in Christ. He is still a conflicted sinner living in a fallen world. Nor has he become perfected, or complete in his desire to become like Christ. His old "natural man" rears its ugly head far too often, and he stumbles in temptation and sin continually. In fact, the closer you draw to the Lord, the more aware of your stubborn fallenness you become. Your sensitivity to how far short you fall from the glory of God increases until, like Paul in Romans 7, you cry out, "Oh, who will deliver me from this body of sin and death?" So admitting failure, honestly and humbly, is a hallmark of someone walking closely with their Lord. The nearer you come to His shining glory, the more brightly your sin is exposed.
It should not stop there, however. The apostle makes it clear, that understanding our shortcomings is no excuse to discontinue moving forward. Instead, it should serve as that much more motivation to press on. Listen closely to how he uses himself to exhort us. Not that I have already attained, or am already perfected; but I press on… and, one thing I do, forgetting those things which are behind and reaching forward to those things which are ahead, I press toward the goal for the prize of the upward call of God in Christ Jesus.
Pressing on in the Christian life is the key. It's a word, dioko (dee-o'-ko), that means "to seek after eagerly, to earnestly endeavor to acquire", no matter what the cost. It's what an athlete does even in the throes of physical exhaustion and weakness, or after stumbling and falling. Yes, we are guaranteed to repeatedly come crashing down into the morass of sin. It's in our very DNA. But that is not the overriding fact of our existence. Christ's redemption of us on the Cross supersedes all such failures. We are His. He promises to complete that good work that our faith in Him began. And out of gratitude and love, and the empowerment of His Holy Spirit - our Comforter and Helper - we get back up and move forward. Why does someone run a race? To receive the prize after crossing the finish line. For that reason, Paul likens our time on earth as a running of the race - a race that if we are Christ's, we are sure to finish.
There is another key to pressing onward, and it is found in this phrase: forgetting those things which are behind and reaching forward to those things which are ahead. In Hebrews, it is said another way. Therefore we also, since we are surrounded by so great a cloud of witnesses, let us lay aside every weight, and the sin which so easily ensnares us, and let us run with endurance the race that is set before us, looking unto Jesus, the author and finisher of our faith, who for the joy that was set before Him endured the cross, despising the shame, and has sat down at the right hand of the throne of God. (Hebrews 12:1, 2, NKJV).
Look, as a Christian whose sins have been forgiven by the shedding of the blood of God's own divine Son on the Cross, it is utter blasphemy to think that there is something you have done in your past, or can do in your future, that somehow disqualifies you for forgiveness and eternal life. You are saying, in your misbegotten pride, that Jesus' sacrifice in your place was insufficient to pay the price. He was not of enough value. If you are guilty of such delusional humility, repent of it now, or examine yourself to see if you are truly in the faith. You may, in your stubborn free will, reject the gift, but do not make the outrageous claim that the gift of the gospel of God was not powerful enough to save you. Or that you must add something to it.
What you must do to move forward, to move closer to your God, is forget those things that are behind. Trust completely that your evil deeds have been removed from your Father's eyes, as far as the East is from the West, and look forward in child-like faith to that future day of reunion with the One who loved you so much that He sent His only begotten Son to save you. Pressing on is an act of faith. It is a sublime expression of your complete dependence on and steadfast trust in Christ. It is an acknowledgement that while you cannot live His life here on earth, He can through you.
In doing so, you take your eyes of you and your weakness, and set them on Him and things above, and you press toward the goal for the prize of the upward call of God in Christ Jesus.
There is nothing else worth pursuing, but Him.