Sometimes it's so well protected and hidden that you may catch just a glimpse of it in their eyes in an unguarded moment
They gave up. At best they are in the process of giving up. And, true, some just never engaged in the first place. Life can be hard. Maybe we've all been at that point sometime in our lives.
It's a sad thing to see. Nobody has to give up. Nobody has to even think of giving up. True, whatever "it" is, some make it, some don't. But, no one was created to fail at "it". Keep in mind that "it" could be, is, different things to different people. The thing is, "it" (I'll stop using quotation marks in a minute) is not up to each of us to define. It was defined by God before He ever brought us into being.
Ephesians 2:10 (NKJV) For we are His workmanship, created in Christ Jesus for good works, which God prepared beforehand that we should walk in them.
God's purpose for us does not change. He will accomplish it through us. We have only to give ourselves to Him so that His purpose will be achieved in our submission and obedience.