In order to understand sin, it is helpful to begin with consideration of its opposite. Righteousness is the opposite of sin. Righteousness, like its opposite, is a term that most people consider to be religious in nature, when it is actually of utmost importance to all people, no matter their beliefs.
Righteousness means “optimal behavior with respect to reality.” Though it happens to be the case that God knows better than anyone what reality is and the path through it that yields the greatest joy, righteousness is only a religious concept for those who already believe in God. Just as with sin, we can debate the application of the term, which is contextualized on the understanding of the individual, but there ought to be no dispute that righteousness is universally good, desirable, and worthwhile, just as we can say that no matter who you are, sin is not good, desirable, or worthwhile. These things are so by definition.
Righteousness leads to what a person wants. Sin leads to anything else. These are not contrived meanings. They have been this way since the beginning of man.
The Hebrew word for sin is “chatah.” It means to miss the mark, or to deviate from the path that would lead you to the target you are aiming at.