What is the most important commandment? What does it mean?

Mark 12:2o-31
29 Jesus answered, “The foremost is, ‘Hear, Israel! The Lord is our God, the Lord is one; 30 and you shall love the Lord your God with all your heart, and with all your soul, and with all your mind, and with all your strength.’ 31 The second is this: ‘You shall love your neighbor as yourself.’ There is no other commandment greater than these.”

John 14:15
“If you love Me, you will keep My commandments.”