2 Corinthians 9:8

God is able to make all grace abound toward you, that you, always having all sufficiency in all things, may have an abundance for every good work. 

When God calls us to do work as a representative, He will also equip us.  If He calls us to talk to someone about being saved, He will give us the words to reach out to that person.  We don’t have to fear that we are not enough because we are not alone.  God will give us the strength and wisdom to accomplish whatever task set before us.