Let your mouth be filled with praise and not complaints. Use your time and energy to exalt the King in your life instead of yourself, and then the peace and the life will come. Jesus took a back seat so that He could pay the price for our sins. He was exalted to the highest position in heaven. Selflessness is learned through submitting ourselves to the will of the Father.
Selfishness comes naturally.
Love is learned by experiencing the love Jesus has for us. Hate comes from not forgiving. The way to getting is giving and He gave all He had. The mind set on the spirit is life and peace. The mind set on the flesh is death.