The number one factor that will determine how effective and productive you are is this: how much time you can spend uninterrupted on one particular task. Do the thinking, get clear on your highest and best use, and reclaim your time. This will enable you not only to be incredibly effective but also to rejuvenate and re-energise.
Taking control of your schedule and your environment enables you to be more present. When you are engaged in work, be fully engaged. When you are not, do your best to fully disengage. Wherever you are, be there. The pauses re-energise you, make you more whole and fulfilled, and therefore make you more effective when you do decide to return to the work. Being effective, and being able to sustain that effectiveness, is how you will build your legacy.