It's about life being a series of hills (one degree of glory to the next) and valleys (the shadow of death), and while we like to focus on the upward side of sanctification, we forget that there's a low for every high. It's about how every valley feels like personal failure, it's about being so tired of yourself that you figure God must be exhausted too, why don't You just let go of me already? I said I'd be holding onto You, but what about when I don't have the strength to do that anymore? It feels like every failure takes me back to square one, and I can't do this much longer.
It's about realizing that it's not about you, that even when you can't hold onto Him, He does not faint or grow weary, He does not stop holding onto you. He does not ever stop seeing you as worth it all, worth His sacrifice, worth bleeding for, worth pulling you up out of the waves, worth going back for again and again. He walked through the valley of the shadow of death too, He's been here before, He specializes in dying, He will guide you through, and when it's too dark for you to see Him, when you can't find Him, even when you're so far away that all there is to see is the marks you left on the ground as you thrashed around, He'll find you. He will find you and lift you up again and again and again.