If you spent 80 days alone with God, fasting and listening... what kind of an impression do you think it would make on you? Moses did exactly that... that is, he spent 80 days alone with God eating nothing; communing only (Deuteronomy 10:10). So, what did the memory of that experience cause him to say?
How about this? "The heavens and the earth belong to God. God has chosen us. God is great, mighty and terrible. He doesn't need anything and so He can't be bribed. He defends the weak and helpless. He is the only worthy object of our praise." Thusly Moses had been stricken by God's infinite transcendence, power, sovereignty, sufficiency, compassion and position. The one and only true and living God is indeed unspeakably wonderful!
The greatness of our God should have an effect on us. Moses was very specific in describing what our response to God should be. Here are verses (about that) which are worth memorizing, "What does the LORD your God require of you, but to fear the LORD your God, to walk in all His ways, and to love Him, and to serve the LORD your God with all your heart and with all your soul, to keep the commandments of the LORD, and His statutes, which I command you this day for your good?" (Deuteronomy 10:12-13).