100%

What is your heart?
It was once said, "The heart is the state of reason and will. The heart is the source, or spring of motives; the seat of passions; the center of thought processes; the spring of conscience.”
It's your personality, your will, mind, emotions, and your conscience; whatever is in your heart is what you will become. It is so profoundly affected by what comes in and takes root there, which is why we need to fill our hearts with God and not with worldly things.
In Proverbs, it talks a lot about the things of our heart. In 2:10 it talks about wisdom, evil and deceit in 6:14, lust, in verse 25, joy, in 12:20, folly, 12:23, anxiousness, in 12:25, happiness, in 15:13, Knowledge, and pride in 16:5. And many more.
As you can see, both the good and the bad things in life come from our hearts. In the Old Testament alone the word heart appears 855 times. What we let in our hearts is very important.
We need to commit all of our heart to the Lord, "Love the Lord your God with all your heart and with all your soul and with all your mind and with all your strength.”
God doesn't want 50%, or 70%, or even 99.9%; God wants all 100%
Does the hymn go, "Seek ye second the kingdom of God..."? No it says, "Seek ye first the kingdom of God..." We are told to keep Jesus first in our lives and we can only do that if our hearts our 100% committed to him.
So we need to give our hearts to God, but how?
First we need to guard our hearts from sin. Martin Luther put it this way:
"To fight against sin is to fight against the devil, the world, and oneself. The fight against oneself is the worst fight of all."
We are called to fight all of these things; we need to deny ourselves daily and take up our cross.
A man named Charles Bridges said the heart is the citadel, and we must be careful to guard it:
“Let it be closely garrisoned. Let the sentinel never be sleeping at it's post...If the citadel is taken, the whole town must surrender. If the heart is seized, the whole man-the affections, desires, motives, pursuits-all will be yielded up. The heart is the vital part of the body. A wound here is instant death. Thus, Spiritually as well as naturally, out of the heart are the issues of life. It is the great vital spring of the soul, the fountains of actions, the center of the seat of principle, both sin and holiness. The natural is a fountain of poison. The purified heart is a wall of living water. As is the fountain, so must be the streams. As the heart, so must be the mouth, the eyes, the feet. Therefore, above all else, keep your heart. Guard the fountain, lest the waters be poisoned...”
Above all else we must keep our hearts.
We need to get close to God.
Lets say you have a little child: he's a good kid, he's respectful, kind, obedient, and he loves his parents. But then he starts hanging around with a foul mouthed, rude, mean kid. Pretty soon your nice, kind kid is going to act like the rude one. He will start to mouth off to his parents, he won't do what he's told, and he'll throw fits.
Who the kid spent the most time with effected him, what he let in his heart affected him.
What are you spending the most time with? Your TV? Your computer? Your friends and family? Or are you spending the most time with God?
Whatever you spend your time with is what you will grow like. Make sure the things you spend your time on are good, and make sure your spending time with God.
How do spend time with God? It's easy.
Listen to him, you don't need to hear him physically to listen. Read his word! Sometimes we act like a young art student who said, "I can't learn to paint till I get a teacher. All I have is a book called How to Paint by Leonardo Da Vinci." He had the teaching of a master. So do we. Read it. Study it. Learn from it.
We also need to pray. God speaks to us though his word, and we need to talk to him through prayer.
Praise him.  You don't need to be at church to sing songs to him. You can sing anywhere, in your car, in the shower, or, if you're like me, while cleaning a pig pen. But singing is not the only way to praise him, tell God how awesome He is, He already knows but doesn't it make you happy to get a compliment?
Lastly, be honest. Tell God you’re not as close to him as you should be, ask him to come in to you, and help you be more committed.