Gladness is different from joy. Joy comes from the presence of the Lord. The Bible says, “in Thy presence is fulness of Joy”. Gladness comes from loving what is right and doing it. Gladness comes from a clear conscience that you did the right thing earlier and so you are not fearful about being questioned or being caught. Gladness is closely related to happiness. If you love the right thing and do what is right you will be happier than all of your friends.
Hebrews 1:9 “You have loved righteousness and hated lawlessness; Therefore God, Your God, has anointed You with the oil of gladness above your companions.”
Not only will you have gladness but you will also not walk in darkness for you will have the light of the Lord.
Psalm 97:11 Light is sown like seed for the righteous and gladness for the upright in heart.