The darkness is what really shows us who we are. It is our darkness that tests our virtues and brings out our true character.

This is true, but I also want to bring it up to another level. If darkness is all the negative feelings that we have, then "darkness is something that helps us grow"

By being scared, we learn to avoid danger.
By being anxious, we have the urge to try to find a solution.
By feeling lonely, we try to reconnect with our family and friends.
By reaching a dead end, we try to find a way out of comfort zone.
etc.

So those dark negative feelings are the ones that actually help us grow. To expand our capabilities, to help us learn the dangers, to navigate us through trials and errors. We should embrace and welcome them. Use the darkness inside us to grow.