You get up in the morning, you go out and give it your best, and you go to bed. Then you get up and do the same thing over again. Results, and your effectiveness, are going to vary because that's life. But as long as you've given your best, and done all you can do, even if the result is less than you hoped for you can still have a clear conscience about your own actions. We are never going to save all the orphans [including good causes that have been orphaned], or feed all the hungry [including those who hunger for knowledge, truth, and justice], or make a home for all the homeless [remembering that it's love that makes a home, and not just a roof and four walls]. The best thing any of us can do in our lives is to go out every day and, in our own way, try to make a difference in the world.
Because eventually you will make a difference...if only to one person. And it will be worth it.