exists no fear in love, rather maturing love drives out the fear because fear has punishment. Now, the one fearing is not matured in agape love (1 John 4:18)
The word discipline παιδεύω (paideuō) means to train, to educate, to discipline, to instruct, to correct. The writer of Hebrews tells us as legitimate children God disciplines us so we share in his holiness (Hebrews 12:10). When he writes we are trained by discipline he speaks of the continuing process of instruction and teaching which sometimes includes punishment or chastisement. The word punishes in this verse speaks to this, literally meaning to scourge, whip, or flog. Also we go through tribulations to receive wisdom and revelation, so to know him more.
God chose us and blessed with all the spiritual blessings in the heavenlies (Ephesians 1:1-14). God put it on my heart to read this chapter over and over again, I can paraphrase it pretty well. It is about what Christ has done for us and how we are blessed in him. From the riches of his grace and glory, and to the praise of his grace, God has blessed us. He sealed us with his Holy Spirit as a guarantor of our inheritance, which he explains in the In the next chapter, making us alive in Christ when we were dead in our trespasses and sin. He did this because he was rich in mercy through his great love, to demonstrated to the ages coming the surpassing riches of his grace in lovingkindness to us in Christ Jesus (Ephesians 1:4-9). We are blessed because God loved us. Faith working through love we are matured to be like him.
for the Lord disciplines the ones he loves and punishes all the one he receives as sons (Hebrews 12:6)
... and why do we put ourselves in danger every hour? accordingly daily, in danger of dying, by your boasting which you have in Christ Jesus. If according human, I fought wild beasts in Ephesus, what have I gained? (1 Corinthians 15:30-32)
Paul writes he faced death everyday so that those he taught would receive life. In other words as Paul was conformed to the death of Christ, and had greater fellowship in the suffering of Christ, he experienced more of the glory of Jesus's life and revelation in the knowledge of him. That spirit of wisdom and revelation, that glory of Christ experienced, given to him in suffering he passed on to the church so that they received life. The hardships that Paul suffered is astounding (2 Corinthians 11:25-30).**
I met in more difficulties, in prison often, in beating above measure, facing death again and again... (2 Corinthians 11:23)
God does punishes us to change our behavior so we become more like him but that is not the only reason we experience tribulations. Five times Paul was literally flogged by the Jews. Was he punished because he did wrong? Even the nature mistreated him, he was shipwrecked three times and once after a shipwreck they were gathering wood to get warm and a poisonous snake bit him. He did not have an easy life by anyone standards but Paul knew deeply of the love of Christ thus he could write,
what can separate us from the love of Christ? Tribulation, or distress or persecution or famine or nakedness or danger or sword? (Romans 8:35,37)
Agape love is the bond that leads us to maturity. Like in the parable of sowing the plant that has deep roots (which Paul expresses as love, Ephesians 3:17, and faith, Colossians 2:6-7) this is the one who bears fruit. With this proper rooting we can have strength to know a greater love of Christ, where the bond is so strong nothing will separate us from him. Then we can endure the thorns meant to choke us out, and grow up mature into the fullness of God, the measure of that being the stature of the fullness of Christ. Truth in love we grow up into him.