"Speak, Lord, for your servant is listening."
Isn't that one of the best phrases, one of the best prayers - so simple, so powerful, so direct? The very first word, "speak", takes away from the one speaking and puts the imperative on the One being spoken to. By the word, "speak", the speaker is already fallen silent. And the speaker addresses himself as "your servant", referring to himself only through the Master he is speaking to.
How much better are these words than something like, "Here I am, Lord, I come to do Your will." Gah, how horrid! Ta da! Here I am! With my trumpet! Now hand me that crosier! I'm here to do Your will - too-ta-too-ta-tooooooooooot!
"...and you do not belong to yourself; for you were bought with a great price..."