By the end of the year, Ishizuka had been offered residency positions in four specialties at Jefferson. He knew he wanted psychiatry, and before starting his internship year at Jefferson, he went to Boston for a day of interviews and was offered a residency position at the Massachusetts Mental Health Center by Professor Jack R. Ewalt, then chairman of the department of psychiatry at Harvard Medical School. Ishizuka was the first candidate to be accepted among 25 residents in psychiatry at the center that year. In celebration, Ishizuka took a trip to Europe on a two-week discount ticket, spending much of his savings in the process.

During this trip, he went to London to visit Marie-France Tourlet, who was engaged to his old friend from prep school, Terusuke Terada, who later became Japan's ambassador to Mexico and South Korea. It was thanks to Marie-France that he met Colette in Paris. He was impressed by the clarity of her thoughts, the open expressiveness of her feelings, the integrity of her judgment and her actions grounded on her strong Christian faith. What impressed him the most however, was her exceptional capacity to give as well as to receive. Her generosity taught Ishizuka to receive, and her openness and responsiveness taught him to give. Her willingness and ability to make a strong commitment to him reassured him and helped him to eventually overcome his strong fear of closeness. They have been happily married for 42 years and have three grown children.

Toward the end of his residency in Boston, Harvard Professors Elvin Semrad and David Riesman encouraged Dr. Ishizuka to undergo further training in psychoanalysis. Dr. Ishizuka seriously considered applying to Boston Institute of Psychoanalysis and going to Mexico City to study under Erich Fromm. However, he was not convinced that psychoanalysis would allow him to preserve his intellectual freedom and independence.

Also during his psychiatric residency, he was offered to become a third-year student at the Museum of Fine Art School by its dean to pursue a professional career as a painter. Professor Jerome Cohen of Harvard Law School recruited him to switch from psychiatric residency to Harvard Law School, where a bilingual lawyer was in high demand. Ishizuka was tempted by both offers but decided to stick to psychiatry and spent his third (elective) year expanding his horizons by studying at the Laboratory of Community Psychiatry under Professor Gerald Caplan.

He managed to convince Dr. Caplan and Dr. Ewalt to allow him to spend his third year of residency working as a management consultant with Arthur D. Little Inc. General James Gavin, then chairman of ADL, gave the young Japanese psychiatrist an opportunity to learn management consulting. Ishizuka participated in several ADL projects as a member of the organizational development team, helping build a strong management team and a culture of creativity. After a year at ADL, Dr. Ishizuka decided to leave psychiatry in 1969 with the dream of helping Japanese companies globalize their operations as a management consultant, using his psychiatric training and understanding of cultures of the East and West.

Ishizuka was also given the opportunity to participate in some teaching activities at organizational behavior section of Harvard Business School. He was introduced to McKinsey & Company, an international consulting firm, which immediately offered Dr. Ishizuka a position in Paris. He spent the next four years working on assignments in Paris, Amsterdam, Toronto and New York. His experience working closely with senior executives of major corporations as a McKinsey consultant taught him to approach a complex problem as an integrated whole and to identify, monitor and control critical key factors for organizational survival and success, according to carefully defined objectives and priorities. While at McKinsey, he met among others a legendary leader of management consulting, Marvin Bower, who took a personal interest in him and even encouraged his pursuit of the Lifetrack project 30 years after Ishizuka had left the firm. Another former McKinsey partner and dear friend, Peter Sosnkowski, has offered him valuable advice and encouragement over the years.

In 1972, Dr. Ishizuka's last McKinsey client, Mitsubishi International Corporation, offered him a position as president and co-founder of a subsidiary responsible for corporate acquisitions and investments. During his fourth year in mergers and acquisitions, a friend and CEO of an international company sought his professional help in depression. Dr. Ishizuka's rewarding experience helping his friend led him to return to the field of psychiatry in 1976.

While in busy merger and acquisition activities, he continued to paint, and in 1974, was accepted as a member and resident artist of the Salmagundi Club, the oldest American professional painters' club.

Dr. Yukio Ishizuka returned to psychiatry asking new questions of his field: What is the objective of therapy? What does it mean to be well? How can we measure and improve well-being? For more than 30 years of full-time clinical practice, he has developed and tested a paradigm of positive psychological health and a corresponding method of therapy in response to these questions. Dr. Ishizuka has applied the analytical skills he developed as a management consultant to clinical psychiatry and integrated concepts from both East and West to create Lifetrack.