We learn from Jesus giving sight to the blind man why God allows negative things to come into our lives (like the current Coronavirus Disease COVID-19 pandemic) and how He uses them for our good and for the good of others.
Just as the people of Israel were given a choice -- allow God to deliver them into the promised land or perish in the desert -- we also have a choice: true life, which is eternal life in the salvation of God, or true death, which is a sinful life in this world.
You let your light shine by knowing your righteousness, which is Christ's righteousness that has been given to you. You show people they are unrighteous but have been offered free salvation from Jesus Christ. You know your good works and know you don't do them to save yourself but because you love God the Father and they bring glory to Him.