A surprising amount of background thinking goes into even the most trivial task we do in our everyday lives. In some cases, such processes are far too complex, that even robots cant do these 'simple tasks'. Let me take the example of a motor task, that of kicking a football. The task principally consists of two parts:

1. Computation: Keeping in mind the goal, I decide on the direction and force the ball is to be given. This consists of a series of simulations run in the mind in quick succession based on different combinations of direction and force possible, and then selecting the best. The task of running a single simulation too, is in some sense complex. It requires some knowledge of elementary physics and some prior experience at kicking.

2.Acting: The brain sends motor signals to the various muscles that would be involved in the process(here, the whole body), directing them. A lot of background computation goes on here. The question arises as to how the brain exactly knows the trajectory of the muscles involved, as to direct them. Spacial knowlegde is necessary; the CNS first must locate the position of the object with respect to the body and represent the initial position of the arm. Recent psychophysical evidence supports the hypothesis that the planning of limbs' movements constitutes an early and separate stage of information processing (Emilio Bizzi). Later, during execution, the dynamics of the musculoskeletal system are controlled in such a way as to enforce the plan of movement within different environmental conditions (Emilio Bizzi).

References
Emilio Bizzi. Motor Control. MITECS 570-571