sequenceDiagram
  Alice->>John: Hello John, how are you?
  loop Every minute
    John-->>Alice: Great!
  end

sequenceDiagram
  participant Alice
  participant Bob
  Alice->John: Hello John, how are you?
  loop Healthcheck
    John->John: Fight against hypochondria
  end
  Note right of John: Rational thoughts <br/>prevail...
  John-->Alice: Great!
  John->Bob: How about you?
  Bob-->John: Jolly good!