The average person puts only 25% of his energy into his work. The world takes off its hat to those who put in more than 50% of their capacity, and stands on its head for those few and far between souls who devote 100%.
Don't be afraid to give your best to what seemingly are small jobs. Every time you conquer one it makes you that much stronger. If you do the little jobs well, the big ones will tend to take care of themselves.