“The fool doth think he is wise, but the wise man knows himself to be a fool.” - William Shakespeare
There are a number of ways in which we could interpret this quote from Shakespeare. For example, one might say he's warning against pride, and they'd be right. However, I think there is another interesting idea incorporated in this quote - the fact that, no matter how much we think we know, there will always be more to learn.
The problem with the fool's approach, using Shakespeare's words, is that he thought he had arrived. When we give in to the belief that we are where we are and we won't be going anywhere - well, that's exactly what happens. We cut off from ourselves the option of growth.
But when we choose to look ahead of ourselves, we will find that there is always more room for growth. In fact, no matter how much you learn for as long as you live, there will always be more - that's just the way the world was created, not to cause you to feel crushed but to enable you to keep growing stronger.
It's important that we apply this to moments of low self-esteem as well. It doesn't matter where you're "arriving," it's still damaging. It's true that there need to be times of rest, but when you're resting it's important not to forget the path in front of us.