Here is a candid plea from the esteemed John Newton — 

I trust I have a remembrance in your prayers. I need them much: my service is great. It is, indeed, no small thing to stand between God and the people, to divide the word of truth aright, to give every one portion, to withstand the counter tides of opposition and popularity, and to press those truths upon others, the power of which, I, at times, feel so little of in my own soul. A cold, corrupt heart is uncomfortable company in the pulpit. Yet, in the midst of all my fears and unworthiness, I am enabled to cleave to the promise, and to rely on the power of the great Redeemer.