There are at least two sides to this idea: stop worrying; start learning.
The first is that worry, or more generally, stress, will hamper, or even halt your ability to learn anything.
You know times in which you have been worried and you practically panic. Even the simplest tasks become difficult when we aren’t thinking straight. The more we worry about, “Where did I put my keys!” the more we can’t think about where we might have put the keys. It is counterproductive.