Stacie -- My first thought when I read your post was that you may not be eating enough to allow for very intense workouts... For intense workouts you need to be fueled properly with good carbs and low fat proteins.... Eating a bit before and after your workout is important. Also, when you first start working out, sometimes but not all the time, depending on your level of fitness, until you are in better shape you will be tired for a while after your workouts. Once you get used to working out you will feel rejuvinated afterwards I promise
... Take care and keep us posted on your progress...