How can you make a difference in someone life

The other day I woke up in sort of a cranky mood.  I don't know why I was feeling the way I was feeling I just wasn't happy.  I think we all have those days when we feel like the world is so hard and life just keeps kicking you down every time you try to make a little progress.  For me thing's got, sort of crappy when my job closed and relocated up north leaving me unemployed.  My own personal situation I have to drive a good distance of travel back and forth from school.  My classes aren't going like I like want them to.  Money is so tight for me.  So I just woke up upset about my life.  Anyway as that day continued I stopped at Wendy's to get something to eat but before that I had gotten some gas and I saw a homeless man looking for bottles.  I wondered what things he did in his life that brought him to the point where he is that he has to dig through trash for bottles.  I left the gas station and proceed to Wendy's I sat in there and ate my food still kind of upset thinking about my own life BUT that homeless made it down to Wendy's and he came into the diner room area I think to just get out of the cold for a minute and I looked at him and I saw him bend over and pick up and eat a french fry off the ground that someone had stepped.  I couldn't believe my eyes that man was that hungry that he ate a stepped on french fry.  I walked over to him and said let me buy you lunch.  He smiled, and said thank you he so grateful.  After that I felt good about myself, I had helped someone that was in need.  My problems were not as big of deal anymore.  So my friends what have you done in your life, that has made a small difference?