It makes a difference how you eat.  Is your diet balanced?  This might make a difference in your energy level.  Lately, I have not been eating too well and running out of energy really quickly.  My wife’s diet has affected my meals:  we usually eat together and she has cut down on her cigarettes significantly.  Until recently she has been filling up on matzohs and other crunchy food.  All this has affected my diet for I usually make one or two good meals a day.  And often she does not want to eat for she has filled her belly on something else although not a very balanced meal.  She had to have something in her mouth to pacify her nicotine cravings.  She might be past this stage so we might eat together more normally.  I am hoping returning to a more balanced diet will return my energy level.  It does make a difference in how you eat.