A flower must open to receive the sunlight, if not, it will die.
We have to open our hearts to God, to receive everything he has for us. We must be opened to receive not only the blessings, but anything God wants to give us, including his discipline. The discipline from God is also a part of the light he has for us, because it produces a fruit of holiness in us. His light could feel sometimes, like burning for us, but that burning will burn all the things in us, which are not welcome in his presence. We can not and should not be open only when we want the good and positive things from God.
God’s discipline is like medicine for us. It could be bitter in our mouth, but it does something good for our bodies, and latter, makes us feel and be better. His discipline is a part of his light for us. His discipline will make us to be like a beautiful flower open up to him, to receive his glorious light.