Presence generally implies an attention or focus on our existence in our body here and now. But, presence can just mean our existence in the space our body is occupying regardless of anything we are paying attention to or thinking about. We cannot not be present in the space all the time. We are always here, i.e., wherever our body is, which is our only person.
So, it never matters that we are lost in space, daydreaming in our head. That will never affect what we are doing because doing is physical activity now. The present moment is what makes our presence present.
Feel this. Find a way to recognize that your body is always a whole. Touch your head, neck and torso (or back) to acknowledge their physical connection, neck always attached to head and torso (back) simultaneously. Or look in the mirror or at your shadow. When we zone out, which is most of the time, we are not aware of this head-neck-torso (really head-spine) juncture. Thus, we don’t feel present. But, feeling present and being present are two different things.
Knowing that we are present in the space all the time is useful in understanding why we can never be somewhere we aren’t, and, therefore, doing something other than what we are currently, physically doing. In my opinion, it is this misperception that confuses us into believing (quite naturally and subconsciously) that we can be in some action our thoughts are so sure we should be in. Nevertheless, it is physically impossible because of our real-time whereabouts; we can only be where we presently are. Since we are rarely aware of our physical reality in this way, it is no surprise that we walk around berating ourselves for not accomplishing the things we wish to be accomplishing. We are missing a crucial piece of information. We don’t realize where we are.