Jens Corssen is a psychologist who is known for saying that the imagination, i.e. the expectation we have of our negotiation partner, makes many a negotiation so difficult. He is also well known for the numerous books he authored.
"Jens Corssen presents the content of his seminar in a convincing and practical way. What's important in your everyday, professional and personal life is to put yourself in an upbeat mood, and to keep control over your inner attitude."