Pugsrule, a couple of days isn't long enough to understand the effects or consequences of a change in your eating program.
Have you thoroughly read the informational book or website for your low-carb eating program of choice? Answers to your questions should be there.
After an introductory period designed to initiate change in your metabolic chemistry (when some people do experience a decrease in energy), the low-carb lifestyle evolves towards a balanced and healthy eating program. It provides sufficient energy for all life activities, including working out.
ALL low-carb plans, including Atkins, emphasize whole foods like fresh vegetables, fresh meats and fish, non-processed cheese, many fruits (like berries, melon), nuts, and, in the maintenance phases, whole grains and dairy.
Furthermore, unlike a "diet" which is a temporary fix, low-carb eating can become a lifestyle that you can live with, ensuring that you'll be able to maintain your hard-won fitness goals.
Never say "diet" again, no matter what good nutritional approach you choose. Learn it well, follow it faithfully, and you'll be a winner for the long term.