There's been times I've seen signs like this in my life and obeyed them.
I don't mean physical signs like the image, instead I mean barriers that have presented themselves, roadblocks and situations where I've felt I should slow down, pull back or quit completely and at in the moment it seemed a perfectly acceptable thing but later in life as I grew in understanding, confidence and skill I began to see it for what it was.
Those occasions were me yielding to the fear of being unsuccessful or not as successful as I would have liked to be. So I stopped, made excuses to myself that I actually believed, and what happened...I failed anyway. Because I had duped myself into believing it was the right thing to do I was even foolish enough to feel good about it. Looking back on that version of me and seeing what I was doing is strong motivation to push much harder now, and it makes me feel some degree of shame in my attitude and behaviors previously.
Nowadays, I understand in no uncertain terms that persistence is an essential factor when it comes to achievement and determination is as well. It's also important to know that when things go wrong, failure or undesirable results occur, we will feel discouraged and have our enthusiasm and energy sapped away. Knowing that it will happen and staying focused on the result despite it is a better way to handle it than surrendering to it.