Surround yourself with people who criticize you. You will learn most from them. They will always push you with their negativity. Don't avoid people who always find a way to criticize you, they are kind of free bug testers working for you.
One is not always motivated through criticism. At times we do not need to be criticized to do more. We just need a simple couragement. Be it constructive or destructive criticism, everything has its time when it is time for you to be praised or encouraged you need the encouragement or praises and when it is time to be criticized you need the criticism. Constant and continuous criticism will however infusion in you some antagonistic spirit and will make you to achieve your goals in a more desperate away.