The rabbi Menachem Mendel Schneerson on dealing with challenges:
"In every challenge or even tragedy, there is an opportunity. And if you train yourself to look for the opportunity, you will be able to take control of the situation and even turn it into a positive or if it can't be turned into something good, at least something good could come out of it."
Source: Likutei Sichot: The Collected Writings of the Lubavitcher Rebbe