In Leviticus 26 we see a fairly extensive list of blessings that God would give Israel for their obedience, followed by an equally extensive list of punishments for their disobedience. The people are left with a pretty clear image of possible results for their choice to follow or not follow, but God has already given them a reason to obey. Take a look at verse 13:
13 I am the Lord your God, who brought you out of the land of Egypt, that you should not be their slaves. And I have broken the bars of your yoke and made you walk erect.Leviticus 26:13, ESV
God had already proven that He wanted the best for the Israelites by freeing them from slavery, and the continued call for the people to follow Him is woven into this chapter. The same message is true for us today. He is the Lord our God; He freed us from our sin, and He is calling us to choose to follow His commands.