The people you know, and who know you in a favorable way, will do more to determine your success, happiness, and level of achievement in life than any other single factor. No one achieves anything of consequence by himself or herself. In life, relationships are everything. My friend Charlie Jones says, ''You will be in five years what you are today except for the books you read and the people you meet.'' Dr. David McClelland, author of The Achieving Society (Van Nostrand, 1961), concluded after 25 years of research at Harvard that your choice of a ''reference group'' would have more to do with your success than anything else. McClelland interviewed graduates of the university, as well as those who had attended his intensive seminars on achievement in American life. He tracked these people for many years. Many of them took what they had learned and did wonderful things with it. They built profitable businesses and successful careers. However, many of the graduates failed to turn the information and ideas they had learned into later success. Why not? When he went back and surveyed them, he found that invariably they had returned to the same group of people they had been associating with before they had taken the advanced courses on achievement. As a result, they went back to the same old ways, the same old habits, the same old customs, and manners of living. Because they were immersed in their old reference groups, nothing changed for them.