With unstoppable march of time death will come to everyone sooner or later but without a fail. When that happens what's going to be left from you? Only memories. If nobody will remember you it's the same as if you never existed in the first place. If you reach this state what was even the point of being born?
That's why it's worth to at least try to make this world a slightly better place, help someone, make someone smile it might result in big change in their lives and what's going to be left of you are fond memories and the fact that your life wasn't meangless.