Although discipline is often defined as an "act of punishing," it's actually based on the same root as disciple i.e. a student. Discipline refers more directly to "a branch of knowledge" and "a system of rules of conduct or method of practice." Punishment is merely the natural result of rejecting what is being taught, often requiring no other person to do the punishing e.g. those who refuse to learn not to touch hot things will themselves be the one that gets burned. The same principle applies to God's offer of salvation.
"Strait is the gate, and narrow is the way, which leadeth unto life"
The author of Hebrews (most probably the apostle Paul - see notes for the next chapter) emphasizes that physical life is meant to be a journey toward spirit life (see the Fact Finder question below; listen also to the Sermons First Day of Unleavened Bread: Beginning The Journey To Salvation and Seventh Day of Unleavened Bread: The Road To Life from our Sermons page). "Let us run with patience the race that is set before us" (Hebrews 12:1 KJV) and "12:13 make straight paths for your feet" (Hebrews 12:13 KJV) reiterates Christ's "7:13 Enter ye in at the strait gate: for wide is the gate, and broad is the way, that leadeth to destruction, and many there be which go in thereat: 7:14 Because strait is the gate, and narrow is the way, which leadeth unto life, and few there be that find it" (Matthew 7:13-14 KJV; see When Will You Be Judged? and I Did It My Way).
"12:1 Wherefore seeing we also are compassed about with so great a cloud of witnesses, let us lay aside every weight, and the sin which doth so easily beset us, and let us run with patience the race that is set before us, 12:2 Looking unto Jesus the author [see The Author of Life] and finisher of our faith; who for the joy that was set before him endured the cross [see Crossing The T], despising the shame, and is set down at the right hand of the throne of God [see What Is Jesus Christ Doing Right Now?]. 12:3 For consider him that endured such contradiction of sinners against himself, lest ye be wearied and faint in your minds.
12:4 Ye have not yet resisted unto blood [see also Why Blood?], striving against sin. 12:5 And ye have forgotten the exhortation which speaketh unto you as unto children, My son, despise not thou the chastening of the Lord, nor faint when thou art rebuked of him [see No Pain, No Gain]:12:6 For whom the Lord loveth he chasteneth, and scourgeth every son whom he receiveth.
12:7 If ye endure chastening, God dealeth with you as with sons; for what son is he whom the father chasteneth not? 12:8 But if ye be without chastisement, whereof all are partakers, then are ye bastards, and not sons. 12:9 Furthermore we have had fathers of our flesh which corrected us, and we gave them reverence: shall we not much rather be in subjection unto the Father of spirits [see Spiritual Conception], and live?
12:10 For they verily for a few days chastened us after their own pleasure; but he for our profit, that we might be partakers of his holiness [see The Holy Father]. 12:11 Now no chastening for the present seemeth to be joyous, but grievous: nevertheless afterward it yieldeth the peaceable fruit of righteousness unto them which are exercised thereby.
12:12 Wherefore lift up the hands which hang down, and the feeble knees; 12:13 And make straight paths for your feet, lest that which is lame be turned out of the way; but let it rather be healed." (Hebrews 12:1-13 KJV)
The Lord's offer of salvation is made once, sooner or later; there are no "second chances" for those who have been given the means to understand (see When Will You Be Judged?). "12:25 See that ye refuse not him that speaketh. For if they escaped not who refused him that spake on earth, much more shall not we escape, if we turn away from him that speaketh from heaven" (Hebrews 12:25 KJV) is a dire warning against refusing God's offer of life.
"12:14 Follow peace with all men, and holiness, without which no man shall see the Lord:
12:15 Looking diligently lest any man fail of the grace of God; lest any root of bitterness springing up trouble you, and thereby many be defiled; 12:16 Lest there be any fornicator, or profane person, as Esau, who for one morsel of meat sold his birthright. 12:17 For ye know how that afterward, when he would have inherited the blessing, he was rejected: for he found no place of repentance, though he sought it carefully with tears.
12:18 For ye are not come unto the mount that might be touched, and that burned with fire, nor unto blackness, and darkness, and tempest, 12:19 And the sound of a trumpet, and the voice of words; which voice they that heard entreated that the word should not be spoken to them any more:
12:20 For they could not endure that which was commanded, And if so much as a beast touch the mountain, it shall be stoned, or thrust through with a dart: 12:21 And so terrible was the sight, that Moses said, I exceedingly fear and quake:
12:22 But ye are come unto mount Sion [see Zionism], and unto the city of the living God [see The City To Come], the heavenly Jerusalem, and to an innumerable company of angels, 12:23 To the general assembly and church of the firstborn [see Christ's Pentecost; listen also to the Sermons Christ's Pentecost and Pentecost, A Day Of Reckoning from our Sermons page], which are written in heaven, and to God the Judge of all, and to the spirits of just men made perfect, 12:24 And to Jesus the mediator of the new covenant [see Why A New Covenant?; listen also to the Sermon The Divorce and Remarriage of Jesus Christ from our Sermons page], and to the blood of sprinkling, that speaketh better things than that of Abel.
12:25 See that ye refuse not him that speaketh. For if they escaped not who refused him that spake on earth, much more shall not we escape, if we turn away from him that speaketh from heaven [see also The Ancient of Days]: 12:26 Whose voice then shook the earth: but now he hath promised, saying, Yet once more I shake not the earth only, but also heaven. 12:27 And this word, Yet once more, signifieth the removing of those things that are shaken, as of things that are made, that those things which cannot be shaken may remain.
12:28 Wherefore we receiving a kingdom which cannot be moved [see also The Coming World Dictator], let us have grace, whereby we may serve God acceptably with reverence and godly fear: 12:29 For our God is a consuming fire." (Hebrews 12:14-29 KJV)
Fact Finder: What is a true believer?
See Growing In The Grace And Knowledge