People don't always say nice things. There will always be someone to discourage you, drag you down, and attempt to keep you from your goals. But the most empowering thing to remember is that you're in charge of you, and you have the power to move forward while they stay behind you. And they can say whatever they want back there, because you are going places and they can't stop you.
Feel free to share this with someone who needs some motivation to move forward and keep those "talk behind your back"ers where they belong.