I always had people ask me that same question when I was in the Army - "You act like you can change the whole Army by the way you do and say things - why do you think you can change it by yourself?..."
My answer was simple - we move around alot. I don't need to change the whole Army at once. I just need to change one or two good people, good Soldiers, in the assignment that I'm in right then. And I'll move. Change one or two more - make a difference for them. Teach them what's right, when to do what, how to accept responsibility for their actions and the actions of their own Soldiers...
...and move again...
Before you know it, 10 years down the road, I've affected and changed maybe 20~30 Soldiers. by that time, they're getting up there in rank, and maybe they remember some of the lessons I taught them, and lead the way they're supposed to. Maybe they're affecting or changing one or two MORE Soldiers at every duty assignment... and those one or two gain some rank...
In the course of 5 years, I could have changed a dozen people, made them good - or great - leaders. In the course of 10 years, that "trickle-down" effect on that might equate to 3 dozen Soldiers.
After 20 years, it might have been something like 12 dozen... Who knows?
I know I saved the good ones, got rid of the bad ones, and did the very best I could with what I had. I live that way to this day, and change what I can.
"God grant me the serenity to accept the things I cannot change, the courage to change the things I can, and the wisdom to know the difference."
The "courage" and "wisdom" parts of that phrase is paramount. <thumbsup>