God did not choose you to see your knowledge, money, beauty, personality, cast etc. But He choose when you were unformed (Galatians 1:15). 

     So don't say I am tall or small, thin or fat, fair or black, rich or poor, smart or ugly, weak or strong. Just do for what you are called. Because it is the Lord who make us like this (Exodus 4:11). 

     If God has choose you without any merit or perfection, You should also serve Him without any fear and excuse.