So, to find flow, you need to choose one single goal; make sure your goal is meaningful to you; and try to push yourself to the edge of your abilities. Once you have created these conditions, and you hit flow, you can recognize it because it's a distinctive mental state. You feel you are purely present in the moment. You experience a loss of self-consciousness. In this state it's like your ego has vanished and you have merged with the task like you are the rock you are climbing.

— Stolen Focus by Johann Hari (Page 56)