Numbers 8:17 For all the firstborn of the children of Israel are mine, both man and beast: on the day that I smote every firstborn in the land of Egypt I sanctified them for myself.
Pretty regular reminder in the book of Numbers that the firstborn belong to Him. He had spared them. They were to be sanctified to Him. I think as you read the book you should realize that if you are saved you are His. He bought you. He rescued you. You owe Him your life. Your life should be lived for Him.
Is that how you look at it. Do you see that spirit and live like that. If not should today be the day that you decide to serve God.