His teaching is significantly influenced by the work of Carlos Castaneda.
His most famous and influential work, The Four Agreements, was published in 1997 and has sold around 4 million copies. It was featured on the Oprah television show, and advocates personal freedom from agreements and beliefs that we have made with ourselves and others that are creating limitation and unhappiness in our lives. Ultimately, it is about finding one’s own integrity, self-love, and peace by way of absolving oneself from responsibility for the woes of others. The Four Agreements are:
- Be Impeccable With Your Word.
- Don’t Take Anything Personally.
- Don’t Make Assumptions.
- Always Do Your Best.
Ruiz also wrote a companion book to The Four Agreements. He then wrote several other books, including The Voice of Knowledge, Prayers, and The Mastery of Love.
Ruiz has subsequently released a sequel, The Fifth Agreement, which adds a further agreement:
- 5. Be Skeptical but Learn to Listen.
In Mary Carroll Nelson’s Beyond Fear, he discusses some of his beliefs through a series of interviews, including his belief in the legend of Atlantis; his belief that the sun entered its sixth age on January 11, 1992, which should lead to a new age for humanity; and his belief in the spiritual power of the pyramid of the sun at Teotihuacan. Fluent in Spanish and English, he often lectures and leads retreats in the United States. Many of his students are American.
In 2002 he suffered a massive heart attack, and spent nine weeks in a coma, but recovered although he was in pain for the next 8 years. He has handed the Eagle-Knight lineage over to his son Don José Luis. On October 9, 2010, Ruiz received a heart transplant at a hospital in Los Angeles, California. He was at a retreat in Wimberley, Texas, at the Lotus Ranch when he found out that a heart was available and had to charter a plane to get back to Los Angeles.