"I said a word I should not have said, and media drives me a little bit nuts to make a big deal about it," Sanders told NBC's Harry Smith during a sit-down interview in his Burlington home. "We're going to get back into the groove of a very vigorous campaign. I love doing rallies and I love doing town meetings."
The 78-year-old presidential candidate said he would "start off slower and build up and build up and build up."
Sanders' comments appeared to contradict what he told reporters outside his house on Tuesday after returning from an appointment with a cardiologist. In those remarks, according to a video released by CNN, the candidate said he would "probably not do three or four rallies a day" anymore.
"I think we're going to change the nature of the campaign a bit," he said. "Make sure that I have the strength to do what I have to do."
In an interview with Seven Days on Tuesday, Weaver said he had not been aware at the time the campaign released that statement that Sanders had suffered a heart attack. "No, I don't believe we did know that. I certainly didn't know that," Weaver said, adding, "I personally did not know that. No, I did not."
In Wednesday's interview with NBC, Sanders told Smith that the doctor who first treated him at an urgent care center in Las Vegas had told him at the time that he had experienced a heart attack.
In text messages after the interview aired, Weaver said he stood by his earlier assertion. Asked how he had not known what the doctor had told his boss, Weaver said, "I was not in the room with him. I put out the most accurate information I had at the time in the interest of providing updates."
Weaver would not say whether Sanders reviewed the "chest discomfort" statement before it was released.
In the NBC interview, Sanders said that questions about his campaign's transparency were nothing more than "a media thing."
"That's nonsense," he said, adding, "The first thing that we're trying to do is understand what's going on and not run to the New York Times and have to report every 15 minutes. You know, this is not a baseball game. So I think we acted absolutely appropriately."