Peter's refusal to let Jesus wash his feet came from a knowledge that he was totally unworthy to have the sinless Son of God serve him as a common servant would. 

Peter was correct in his assessment of his relative worth, but what he missed was that God doesn't minister to us because of our worth but because of His love.

Peter's attitude may have looked holy and humble, he was actually resisting God's will and committing an act of pride. Pride is not only exalting yourself above what is proper, but also, it can be debasing yourself below what is proper. Pride is simply self-centeredness or being self-willed instead of God-centered and submitted to God's will. Peter should have been humble enough to know that Jesus knew what He was doing and he should have submitted himself to God's will.

Some people refuse to let God bless them, thinking they are unworthy of His favor. While it is true that our actions don't warrant God's goodness, a truly humble person will receive the Lord's blessings as an expression of His love and grace toward them. Misguided humility is every bit as damaging as exaggerated pride.

Peter wanted to serve Jesus, but did not want to be served by Jesus. Jesus was telling Peter that unless he received His ministry to him, Peter would be unfit to serve Him. We cannot cleanse ourselves or others. We are totally dependent on the work of God's grace in our lives. 

Then are we equipped to minister to others. Before we can be the blessing that we desire to be to God or to others, we have to let God be the blessing to us that He desires to be.