here's an oft repeated story about a young man who enjoyed walking on the beach.  One day,  he saw an older man in the distance reaching down to pick something up, then jogging toward the water to throw it in.

Over and over, the same scene repeated.  The older man picked something up, ran toward the water, threw it in, and then jogged back to pick up another. 

The young man finally got close enough to see that the old man was picking starfishes up off the beach and, in an effort to save them from certain death under the sun,  was throwing them back into the surf.

The younger man chuckled and yelled out "What's wrong with you?  Don't you know that there are thousands of starfish on the beach?  You can't possibly make a difference."

The older man, without a word, bent down to pick up another starfish.  He ran toward the water and threw it in. 

He came back and looked the young man in the eye, calmly saying "I made a difference to that one."

It is the greatest of all mistakes to do nothing because you can do only a little.  Do what you can.

                                                          - Sydney Smith