And now, O Israel, what does the LORD your God ask of you but to fear the LORD your God, to walk in all his ways, to love him, to serve the LORD your God with all your heart and with all your soul. Deuteronomy 10:12
This verse really sums it up, doesn't it? Fear God, Love God, Serve God. If we could just do this every minute of every hour of every day we would be perfect. Since that is not going to happen in this lifetime, we can at least do our best to do those three things.
How do we fear God?
To fear God is basically to respect Him for His power and glory, to be aware that He will judge us. It is also the opposite of the fear of man. If we are living in the fear of man, we are constantly thinking what will people think if I do this? If we are living in the fear of God, we will be asking, "What does God think of this?" "Will this thought or action please Him?" It is also to hate evil.
I like to think of it as similar to my relationship with my father. I can talk to him, ask for advice, play with him-- I'm not terrified to be near him. But, on the other hand, I want to do things that I know will please him and not upset him. I have a sort of "fear" of what will happen if I disobey him-- but not of him himself.
To fear the LORD is to hate evil; I hate pride and arrogance, evil behavior and perverse speech. Proverbs 8:13
"The fear of the LORD is the beginning of wisdom, and knowledge of the Holy One is understanding. Proverbs :10
How do we love God?
Love is expressed by actions-- in this case, by obeying His commandments. This is how He loves us-- by His actions, especially of dieing on the cross for our sins.
Also, if we love someone, we are going to spend a considerable amount of time with them, are we not? So then, it would seem to follow that if we love God, we will be spending time talking to Him and reading His word to find out more about Him and about His commands. Another thing that we do when we love someone is tell others about how wonderful they are. So it is with God-- if we really love Him, we will be willing and eager to tell others about Him. And we will be praising Him for all He has done for us.
And you shall love the LORD your God with all your heart, with all your soul, with all your mind, and with all your strength.’ This is the first commandment. Mark 12:30
How do we serve God?
To be used by Him, and to devote our lives to Him. To do all that we can for His cause. I think it may also mean to worship Him.
Jesus answered, "It is written: 'Worship the Lord your God and serve him only. Luke 4:8
Do not allow what you consider good to be spoken of as evil. For the kingdom of God is not a matter of eating and drinking, but of righteousness, peace and joy in the Holy Spirit, because anyone who serves Christ in this way is pleasing to God and approved by men. Romans 14:16-18