So where were you on the night of Nov. 7, 1991? I was in Madison Square Garden, watching Pat Riley bring his Knicks and the visiting Orlando Magic together to say a pregame prayer for Magic Johnson on the day Johnson revealed that he had tested positive for H.I.V., the virus that causes AIDS.

That was 20 years ago Monday, and if your first thought is, ‘Oh, my, how time flies,’ consider the alternative likelihood that Johnson has relished every single day since he looked into television cameras broadcasting live around the world and said, “Because of the H.I.V. virus that I have attained, I will have to retire from the Lakers today.”

Yes, the verb was mangled, but that was part of Johnson’s charm, his standing — then and now — as the most positive force of energy to ever hit professional basketball. He was 32 and tried to be upbeat that day, flashing the trademark smile that Johnson’s friends and colleagues feared they wouldn’t see for long.

“All of us thought it was a death sentence,” Riley said.

That morning, Riley was in his office at the Knicks’ Westchester County training base when Lon Rosen, Johnson’s agent, called with the news. Riley hung up the phone and leaned back in his chair, in disbelief.