Whatever purpose that is, it should be paramount in your life. When you do something that does not further that purpose which is not required just to stay alive should be avoided. So while you obviously must eat to stay alive, you must not eat more than you need to further your purpose. Diversions (things done for the purpose of being amused) should be avoided (unless, of course, you have determined that being amused is your purpose in life).
I believe that we are all called upon to serve the Creator. Lay persons may best do this by devoting their lives to helping the needy. How you help the needy will depend upon your skills and talents. For instance, a physician may heal the needy, a carpenter may build housing for the needy. In the absence of specialized skills, you may simply provide financial support to the neediest among us, including anyone who is more needy than you.
The same as any other creature like the deer and elephants. To exist for no good reason, to eat, reproduce, raise young, experience life and form relationships with other creatures. You don't need a better reason, just work at enjoying the day, enjoying people, taking care of your children and lunch. Lunch is as important as anything else even breakfast, which is the most important meal of the day.
to pass down ever changing genitic information
to live life to the fullest and ultimately be happy
greed.
