You should always take what your MD prescribes for you, or at least make he/ she aware if you are not. I am a former hospital dietitian, and I have been on both of the meds you mention. The atenolol always made me fell lethargic, and made it difficult to exercise. It slowed my pulse. I only take lisinopril now for many years, and never feel tired from it. I do have a high pulse though. You should discuss this with your MD and perhaps he will elminate one of the meds and change the doseage of the other, Perhaps he will put you on a different one enitrely. You can't "play doctor" with meds like this.