Exercise! Yes, exercise. Get your butt up off the couch and get in shape. Keeping physically fit will not only reduce fat and cholesterol and help you live longer, but it will also help your voice! Some voice over sessions can take hours. Time is money. If you keep having to take breaks during a session, you are costing the production team valuable minutes. When you have the stamina to keep up the voice and your acting, the better your performance will be and the better the likely hood that you'll get called in to work again.