we have to know dark to appreciate light,
we have to know sickness to appreciate health.
When we have challenges we can appreciate the solutions,
when we experience lack we can then appreciate abundance.
We have to see the dark side to gain appreciation for the brighter side. Imagine if there was only light, if the sun remained out all the time with no time for darkness. The plants wouldn't live, animals wouldn't live and life as we know it wold be very different. Just like the yin and the yang we need to have the good with the bad. The balance of life that allows us to have calm with excited, happy with sad and sickness with health.
So the next time you are in a difficult place remember, this too shall pass as is the delicate balance of the Universe.