Doctor's orders

Old Zeb was 91 when he went to the doctor for a physical. Seems he did not feel as pert as he use to. After checking him over, the doctor gave him a prescription, some advice, collected his fee and told him to come back in six months.
From time to time the doctor saw Zeb around town, just living it up, with a lady young enough to be his granddaughter on his arm. Zeb was back for his six month appointment. The doctor was impressed and told Zeb, that he had seen him around and he seemed mighty spry. "Just took your advice doc, You said to get me a hot mama and be cheerful". Whoa Zeb, that not what I said. I said :" you have a heart murmur, be careful."