Be careful how you spend your energy - you only have so much left. Do you ever feel like you’re just spinning your wheels? Wasting energy and not actually going anywhere? So many people are too quick to spend their energy on actions before they have any idea of what they are really trying to accomplish. What Seneca is saying is to be forward looking; have an end in mind before you activate yourself. Don’t get busy doing something until you can clearly see what it is you’re going for and how you can get it done.