Most people have certain values or principles by which they choose to live. They may be based on religious tenets, or simply reflect an upbringing and education in which "proper" behavior and attitudes to others, towards their work, and towards the broader society form the basis for their outlook on life. This is often referred to as a "code of ethics." It provides a moral compass that individuals use in making decisions, for example, whether to purchase the item that was manufactured using environmentally friendly methods, even though it costs more than the competing item that was manufactured by a company with a reputation for using more environmentally destructive practices.
The oldest code of ethics could be that found in the Bible, specifically Matthew 7:12: "So in everything, do to others what you would have them do to you, for this sums up the Law and the Prophets." This "golden rule" has provided the basis for many personal statements of ethics, along with reference to the Ten Commandmants.
Personal ethical statements, however, need have no reference to theology. They could, and usually do, simply reflect a commitment to do what one believes is "right," regardless of the consequences.