The HUGE truths of who God is, what His creation is and is for, how small we are, and what His promises are; they are often put up in our heads and only breifly thought about. But these are the biggest, most important things He tells us. We are made for His pleasure. He will take care of us, but He is our God all is for Him. These are the truths that need to come in and wipe out any desires when you are tempted. To remind you to give it your all. He will not take your second best, he wants your all.
When you study these truths and think about what that really means you should get a new sense of what you have to do. Let go. Tell Him "Father I am wasting time, don't let me do this, however you'll do it, use me. Take me Lord take me, take my heart it's yours. For you God; your kindom come. Your will not mine. Most of these thoughts are not mine they are counterproductive. Take them from me God. Take me in completely." Surrender your fears and doubts in that moment knowing He will take them.
Malachi 1:6-14
A son honors his father, and a servant his master. If then I am a Father, where is My honor? And if I am a Master, where is the [reverent] fear due Me? says the Lord of hosts to you, O priests, who despise My name. You say, How and in what way have we despised Your name?
By offering polluted food upon My altar. And you ask, How have we polluted it and profaned You? By thinking that the table of the Lord is contemptible and may be despised.
When you [priests] offer blind [animals] for sacrifice, is it not evil? And when you offer the lame and the sick, is it not evil? Present such a thing [a blind or lame or sick animal] now to your governor [in payment of your taxes, and see what will happen]. Will he be pleased with you? Or will he receive you graciously? says the Lord of hosts.
Now then, I [Malachi] beg [you priests], entreat God [earnestly] that He will be gracious to us. With such a gift from your hand [as a defective animal for sacrifice], will He accept it or show favor to any of you? says the Lord of hosts.
Oh, that there were even one among you [whose duty it is to minister to Me] who would shut the doors, that you might not kindle fire on My altar to no purpose [an empty, futile, fruitless pretense]! I have no pleasure in you, says the Lord of hosts, nor will I accept an offering from your hand.
For from the rising of the sun to its setting My name shall be great among the nations, and in every place incense shall be offered to My name, and indeed a pure offering; for My name shall be great among the nations, says the Lord of hosts.
But you [priests] profane it when [by your actions] you say, The table of the Lord is polluted, and the fruit of it, its food, is contemptible and may be despised.
You say also, Behold, what a drudgery and weariness this is! And you have sniffed at it, says the Lord of hosts. And you have brought that which was taken by violence, or the lame or the sick; this you bring as an offering! Shall I accept this from your hand? says the Lord. But cursed is the [cheating] deceiver who has a male in his flock and vows to offer it, yet sacrifices to the [sovereign] Lord a blemished or diseased thing! For I am a great King, says the Lord of hosts, and My name is terrible and to be [reverently] feared among the nations.
Why would we in this life give Him our second best!? How could we see the sacrifice we need to give Him, then turn to look at the second best sacrifice and choose that insead!? When we feel we can't give it any more, we are being silly. Constantly ask Him to TAKE more. To show you HOW to give more and more. Wherever your time and attention is, there is your treasure, and there your heart will be also. It's a heart issue most have. Serve Him because these HUGE truths we must live by show you why. Not just because. Not just because it's routine and you have to. Ask Him to take away any self reasons to do His work. We ALL wantt he biggest peice of cake. We all, deep down, want to be first in line. That's our human inclination. Drown that out with those larger truths. They ARE reality. Ask Him to help you put them to heart.
What will the world think of your God when they see you not giving Him your all? They will think "Some God He is, if He doesn't deserve your 100%." He says better is it for you to shut the door to the temple than to do this and blasphemise His name.
And do not be ashamed to put your heart where it belongs. Do not put Him inside a box, and push push push diligently in seeking Him repeat and repeat and repeat what is on your heart. Demand He be glorified by you and your body be used completely for His glory. Don't ever limit what you think He'll use you for.
I need to experience what Mark did and get some confidence, huh? 
