In Rom 8:19 he uses a wonderful word for eager expectation.  It is apokaradokia (<G603>) and it describes the attitude of a man who scans the horizon with head thrust forward, eagerly searching the distance for the first signs of the dawn break of glory. (William Barclay's Daily Study Bible)

“True, we must suffer with Christ, if we would partake of His glory; but what of that?  For if such sufferings are set over against the coming glory, they sink into insignificance.” (A Commentary on the Old and New Testaments by Robert Jamieson, A. R. Fausset and David Brown)

"When I see a bird that walks like a duck and swims like a duck and quacks like a duck, I call that bird a duck." Indiana poet James Whitcomb Riley (1849–1916)

“The call is not to be taken lightly.  For a person to possess knowledge is not enough.  He must be sure that he is properly called.  Those who operate without a proper call seek no good purpose.  God does not bless their labors.  They may be good preachers, but they do not edify.  Many of the fanatics of our day pronounce words of faith, but they bear no good fruit, because their purpose is to turn men to their perverse opinions.  On the other hand, those who have a divine call must suffer a good deal of opposition in order that they may become fortified against the running attacks of the devil and the world.”

Joint heirs - That we may know it is a great inheritance which God will give us for he hath given a great one to his Son.  If we suffer with him - Willingly and cheerfully, for righteousness' sake.  This is a new proposition, referring to what follows. (John Wesley)

But Paul means, that the Spirit of God gives us such a testimony, that when he is our guide and teacher, our spirit is made assured of the adoption of God: for our mind of its own self, without the preceding testimony of the Spirit, could not convey to us this assurance. (John Calvin)

In New Testament times adopted sons enjoyed the same privileges as natural-born sons. So, instead of cowering in slave-like fear, Christians can approach God in an intimate way calling Him Abba, Father. Walvoord, J. F., Zuck, R. B., & Dallas Theological Seminary. (1983-c1985). The Bible knowledge commentary : An exposition of the scriptures (2:471). Wheaton, IL: Victor Books.

For as many as are led by the Spirit, etc. - No man who has not Divine assistance can either find the way to heaven, or walk in it when found.  As Christ, by his sacrificial offering, has opened the kingdom of God to all believers; and, as a mediator, transacts the concerns of their kingdom before the throne; so the Spirit of God is the great agent here below, to enlighten, quicken, strengthen, and guide the true disciples of Christ; and all that are born of this Spirit are led and guided by it; and none can pretend to be the children of God who are not thus guided. (Dr. Adam Clarke)

Rom 8:12 ⁽¹⁴⁾ Therefore, brethren, we are debtors, not to the flesh, to live after the flesh.

(14) An exhortation to oppress the flesh daily more and more by the power of the Spirit of regeneration, because (he says) you are debtors to God, in that you have received so many benefits from him. (Geneva Bible Translatioon Notes)

"I ought to pray before seeing any one.  Often when I sleep long, or meet with others early, it is eleven or twelve o'clock before I begin secret prayer.  This is a wretched system.  It is unscriptural.  Christ arose before day and went into a solitary place. David says: ‘Early will I seek thee'; ‘Thou shalt early hear m y voice.' Family prayer loses much of its power and sweetness, and I can do no good to those who come to seek from me.  The conscience feels guilty, the soul unfed, the lamp not trimmed.  Then when in secret prayer the soul is often out of tune, I feel it is far better to begin with God—to see his face first, to get my soul near him before it is near another.” (Robert Murray M'Cheyne)

Now there is only one rank in God’s army, Lord, and that is thankfully already taken!

Rom 8:12 ⁽¹⁴⁾ Therefore, brethren, we are debtors, not to the flesh, to live after the flesh.

(14) An exhortation to oppress the flesh daily more and more by the power of the Spirit of regeneration, because (he says) you are debtors to God, in that you have received so many benefits from him.

If the Spirit be in us, Christ is in us. He dwells in the heart by faith. Grace in the soul is its new nature; the soul is alive to God, and has begun its holy happiness which shall endure for ever. (Matthew Henry)

Sins are not a list of petty irritations drawn up for the sake of a jealous God.  They are, rather, a description of the impediments to spiritual growth.  We are the ones who suffer if we sin, by forfeiting the development of character and Christlikeness that would have resulted if we had not sinned. Muck, T. C. (1989). Vol. 19: Sins of the body : Ministry in a sexual society