Service changes people. It refines, purifies, gives a finer perspective, and brings out the best in each one of us. It gets us looking outward instead of inward. Righteous service is the expression of true charity, such as the Savior showed.
Much more prevalent than physical fear is the fear of criticism, rejection, and verbal opposition.
All sin is selfish, whether it be lying, cheating, stealing, immorality, covetousness, or idleness. Sin is for one's own ends, not for another's-certainly not for the Lord's ends.
As we immerse ourselves in the service of others, we find our spiritual selves and come unto Him.