The Israelites realized that they weren’t following the Lord as they should be. Immediately they were remorseful. 
Nehemiah didn’t want the people to stay in a place of sadness, regret and grief. He told them to rise up, to bask in the joy of the Lord. 
Satan would love to see God’s children go through life oppressed and defeated for past sin. But God calls his own to walk in newness of life, to move forward in grace. 
Repent and move on. There is strength in the joy of the Lord. 
Scripture taken from:

Nehemiah 8:9-12