I answer, first, because of the fullness of Christ. You may very well ask what you will when you abide in Christ, because whatever you may require is already lodged in Him. Good Bishop Hall worked out this thought in a famous passage. I will give you the substance of it—
Do you desire the Grace of the Spirit? Go to your Lord’s anointing.
Do you seek holiness? Go to His example.
Do you desire pardon of sin? Look to His blood.
Do you need mortification of sin? Look to His Crucifixion.
Do you need to be buried to the world? Go to His tomb.
Do you want to feel the fullness of a heavenly life? Behold His Resurrection.
Would you rise above the world? Mark His Ascension.
Would you contemplate heavenly things? Remember His sitting at the right hand of God and know that He “has raised us up together and made us sit together in heavenly places.”

I see clearly enough why the branch gets all it wants while it abides in the stem, since all it wants is already in the stem and is placed there for the sake of the branch. What does the branch want more than the stem can give it? If it did want more it could not get it. For it has no other means of living but by sucking its life out of the stem. O my precious Lord, if I want anything which is not in You, I desire always to be without it. I desire to be denied a wish which wanders outside of Yourself. But if the supply of my desire is already in You for me, why should I go elsewhere? You are my All—where else should I look? Beloved, “it pleased the Father that in Him should all fullness dwell,” and the good pleasure of the Father is our good pleasure, also—we are glad to draw everything from Jesus. We feel sure that, ask what we will, we shall have it, since He has it ready for us.