David began teaching memory techniques in 1997 in the Fire Department and soon moved on to schools, universities, associations and companies.
In 1999, he left the Fire Department to become a professional speaker.
He has spoken to more than 500,000 people in 60 countries. Venues include Caesars Palace, Las Vegas, Harvard Club, NYC and Wembley, London.
In 2003, he began speaking for CEO mentoring groups and has spoken to over 3500 MDs and CEOs. One of the groups, the Academy for Chief Executives, awarded him their highest accolade - Speaker Hall of Fame.