- Our moral character
- Outside pressure
- The ease of committing the crime
Here's an example: a hardened criminal who hardly has any scrap of moral character has just found out that his life long friend owes thousands of dollars to a mob boss. If his friend's debt is not paid off in 24 hours, he will be killed. Those weigh in pretty heavily on the criminal, so no matter how hard it is to commit the crime, he will try with all of his might to do so and will most likely succeed. Points one and two far outweigh number three, so he will tip in the direction of crime.
Another example: A clean-cut Mormon guy who majored in accounting at BYU got an excellent job working with a up-and-coming technology company. His wife just got diagnosed with an aggressive form of cancer. Since he is the accountant of this successful company, he can easily move some money around and help pay the medical bills. The outside pressure of his wife's ailment and the easiness of committing the crime will most likely push him beyond the bounds of his moral character.
This is also why we are urged to not put ourselves in situations where it is very easy to do something bad: parties with alcohol, staying out past curfew, addiction to pornography. Just think about Joseph and Potiphar's wife. He ran from the situation that made it very easy to commit sin.