It doesn't matter whether you work for money or work for love, having a purpose in life seems to give a very positive energy to your day.  It seems those who have built a life around working then suddenly retire with no replacement in the way of a hobby or outside interest seem to quickly deteriorate mentally and physically.  Even those feisty folks who stomp around various causes generate personal energy to fuel their fires.  I've known people who have "worked" until their 80's in various capacities and they did so because they wanted to have a reason to get up and go out the door each day.  Others have spent their passion on grandchildren, golf, tennis, dancing, cooking, fishing, politics, traveling...you name it.  It doesn't seem to matter what the activitiy might be, the important thing is the "fire in the belly" when they talk about their interest.  The spark that shines in their eyes, the deeper breath they take all say they are living life to its fullest.