What does Hebrews 12:9 mean?

In this passage, the writer of Hebrews has pointed out that even the great heroes of the faith experienced varying forms of hardship (Hebrews 11:35–38). Jesus Himself was persecuted (Hebrews 2:10; 12:3), despite being sinless (Hebrews 4:15). And yet, Jesus interpreted His experiences as God preparing future joys (Hebrews 12:2). This means that hardship and suffering are not necessarily punishments, or evidence of God's abandonment. On the contrary, loving parents take an active role in "training" their children (Hebrews 12:5–6). When God disciplines, correct, or challenges us, His purpose is to make us more like Him. That's an act of love. In the prior verse, the writer explored the opposite idea: what would it mean if we experienced no discipline at all? Wouldn't that suggest that we're not being treated as sons and daughters by God, implying that we're not really His?

Here, that same idea is explored further. In human parent-child relationships, we look back on parental discipline with respect. We recognize that fathers and mothers correct their children, train them, and challenge them, all for the purpose of guiding their growth. That discipline is rarely appreciated at the time, a point the writer will acknowledge in later verses (Hebrews 12:11). However, once we see the end purpose of that correction, we actually come to appreciate it! If it's possible for a child to respect the discipline of an earthly parent, we should be able to respect the discipline that comes from our Heavenly Father.