以前，看一本书或看一篇文章，你会领悟到这一点；
十年后，你会领悟到的和以前的那个点有所不同。
到底是你成长了，还是你变了？

Is there a limit towards any challenge you faced? How would you define it as a real challenge?

Yes, it is hard to set a certain threshold and follow the routine you planned repetitively, but without it the bar height will fall lower and lower and gradually follows the way you planned it, no expectation at all. While on the other hand, having a strict routine causes you to lose your enthusiasm as you're bounded by the rules you set, you feel challenged, limited by protocols and in repeating manner for each and every cycles before starting to get bored.

How to balance it? You define it.

"We would think that the choices we make now is what would be best for the future, yet in the end we will need to adhere to circumstances when things went south. And we told ourselves, this was the path we chose, there's no turning back, next thing we know, we let regret defines us.

I was reluctant to plan for the future because I do not trust myself to live that long. I have let my youth slipped in exchange for the unnecessaries. And I felt it diminishing as we speak, yet I'm too far down the road to turn back. Time is tickling. I guess that's it.

My worldview is bleak, I know. But nobody's perfect."

-- Christopher Caine