"You leave your fingerprints on the lives you touch."
As people wander through life they often go through bouts of depression. They'll wonder if they've made any impact on the world at all, if their existence means anything, if anyone would notice if they suddenly disappeared. In the end they probably come to the conclusion that no, nobody cares, nobody would wonder where they went if they got up and left, nobody would remember them for long after they died. It's true, it is often very hard to tell if you really matter at all to anyone around you, very hard to tell if they'll realize it once your gone. What people don't realize, is that people don't often tell other people how they've affected them or if they mean a lot to them. The other thing is that people often don't even realize how you've affected them or had an impact on them. With every little interaction, just by being you everyday, you affect those around you. Maybe in very small ways, but you do have an impact. It's like the quote above says, you leave your fingerprints on the lives you touch. There's no telling at all how many people would be different if you had simply never existed. Only God completely knows the extant of how you have influenced people and how you have touched their lives. I find it encouraging just to think about that and know that your life has more meaning than you could possibly understand. Every person matters, every person changes lives, every person would be missed, even if just unconsciously, if they were gone or if they never existed.
Above quote is from Remember Me, quoted by Robert Pattinson. Pattinson quotes Ghandi a lot through the movie, I can't remember if this particular one was a Ghandi quote, or if it was original.