You have probably often heard the saying "Life is hard--but God is good!", that saying reflects much of what Paul is sharing in our verses for today. Life isn't always a cake walk. We struggle to do what's right in God's eyes and yet the selfish parts of us scream that we want it our own way. This is the struggle we face but the glorious news in these verses is the critical point of keeping your hearts and minds set on the Spirit and serving the Lord and pleasing Him.
It is the Spirit of God within that enables us day in and day out to hear the voice of the Lord and to help us understand how we are to walk. It isn't so mysterious that we cannot understand as Jesus said that it is the Holy Spirit that will lead us into all truth and remind us of all Jesus has taught. (see John 16:13) There is life in the Spirit and we are led by the Spirit to fully know and understand that we are the children of God. What comforting news--children of God! Not only children, but chosen by God, adopted into the family! We cry Abba! Father! The word Abba is a very intimate cry as it means "daddy." There have been so many times in my own life when I needed to just crawl into the arms of my Heavenly Father, "Daddy", and have the reminder of being loved as a daughter of God. Even writing this my mind brings up memories of the comfort I received from my Father during those times.
Serving Jesus fervently is not always an easy road, but it is a journey fulling supported, completely provided for, and intimately loved and known by the God who says, "you are mine!"