I appreciate Seneca makes a distinction made between existing and truly living.  That said, I find the work lacking in a proper description of what it means to truly live.  Seneca spends far more words identifying ways in which people waste their time than he does identifying ways to live a meaningful life.  Many of the usual suspects are included on the list of time-wasters.  However, to my surprise, he also includes (if I recall correctly) helping others, running businesses, and making music.  He emphasizes the reward that comes with studying writings of philosophers who have come before you.  To me this seems valuable yet insufficient guidance on what to do with your time rather than wasting it.