When I was working I would do aerobics during my lunch hour and then pick up a some tasty food from the deli which I ate at my desk. I loved potato salad and cucumber and tomato . I always felt great . Wether it was the food I don't know.
Are you fit ? I was back then, but I would think I would be nackered after a workout now, as i am very unfit right now .
Don't give up on your work outs.