There is a mental state called flow, similar in ways to trance and absorption, in which mental focus is fully taken by one task. In the case of flow, the usual focus on a particular goal is replaced by focus on the task itself, losing both oneself and the future by entering fully into the moment and the action itself. In a way, one's state of being merges with the action, so as to become the action. From Wikipedia:
In positive psychology, a flow state, also known colloquially as being in the zone, is the mental state in which a person performing some activity is fully immersed in a feeling of energized focus, full involvement, and enjoyment in the process of the activity. In essence, flow is characterized by the complete absorption in what one does, and a resulting transformation in one's sense of time.
Enjoyment of the activity stems from the experience itself, rather than from what one expects to gain as a result of the action. As such the activity is said to be intrinsically rewarding. Basically one has transcended worry and self-reflection, fully engrossed without question. From my experience, questioning the task can break the flow. From Wikipedia:
Some of the challenges to staying in flow include states of apathy, boredom, and anxiety. The state of apathy is characterized by easy challenges and low skill level requirements, resulting in a general lack of interest in the activity. Boredom is a slightly different state that occurs when challenges are few, but one's skill level exceeds those challenges causing one to seek higher challenges. A state of anxiety occurs when challenges are high enough to exceed perceived skill level, causing distress and uneasiness. These states in general prevent achieving the balance necessary for flow.