Also, read the free fitness book that comes with the news letter. for the PB you only need to be able to run a few yards at full speed. Also it's important not to push yourself. Listen to your body. If you muscles say no, than it is no... it will get better after a while but take this time to give your body time to adept.
You will get your energy back, even I got more energy when I started this lifestyle. (after a few days of carb-flu that is)