Adam Clarke on Psalms 119:16

I will delight myself - The word is very emphatical: אשתעשע eshtaasha, I will skip about and jump for joy.

14. He must exult in God's word as his treasure, live in the spirit of obedience as his work, and ever glory in God, who has called him to such a state of salvation.

15. He must never forget what God has done for him, done in him, and promised farther to do; and he must not forget the promises he had made, and the vows of the Lord that are upon him. Any young man who attends to these fifteen particulars will get his impure way cleansed; victory over his sin; and, if he abide faithful to the Lord that bought him, an eternal heaven at last among them that are sanctified.