The yetzer hara represents the inner impulse or tendency within the human heart to gravitate toward selfish gratification (the word yetzer first appears in Genesis 6:5 where the wickedness of man is described as "every imagination of the thoughts of his heart was only evil continually"). The yetser hatov, on the other hand, represents the inner impulse to do good.
Yetzer is also used in Scripture to refer to something formed or shaped, like pottery fashioned by the hand of a potter. Just as a potter purposes a shape in his or her mind before forming an object, so that which is intended within the mind will shape or form our character and disposition, especially with regard to our relationship with God.
The following prayer appeals to the LORD to help us love His Torah and His mitzvot and also to keep us from the power of the evil inclination within us that pushes us into sin, pride, perversity, tempation, and shame: