It's hard to be able to really apply this principle (competing only with yourself) in real life, as you are bombarded every day by information about other people like you who achieve more. Think about social media for example, or even steemit, when you read your articles and compare them to those of other, more successful bloggers. But once you are able to set yourself free from this unhealthy cycle of comparison, you are truly able to grow by setting some realistic standards for yourself, based on your true capacities.