Margaret Thatcher once ran Britain. John Kennedy’s “Margaret” mostly runs him into the ground. Sen. John Kennedy, R-La., is going viral after posting a tongue-in-cheek workout video introducing followers to “Margaret” — his elliptical trainer named after former British Prime Minister Margaret Thatcher — while wearing a red bandanna and speaking directly to the camera from his Louisiana carport. “Hey X, I have somebody I’d like you to meet,” Kennedy says at the start of the minute-long video posted to social media Friday.“This is Margaret. Margaret is my elliptical trainer. I named Margaret after Margaret Thatcher because both kick butt and take…