The ספר הישר of Rabbeinu Tam speaks of the war between the יצר הרע and one's שכל. Sometimes we use the word שכל to mean common sense but here it means more in that the שכל if used properly will help a person make the right choices. Rabbeinu Tam is reminding us that the יצר and the שכל are two powerful sources within every human being. The struggle between the two is described as an all out war. We should never give ourselves the credit for overcoming the יצר. It is Hashem's kindness that allows us to be victorious over the יצר. It is likely that Hashem sees how hard we are trying to walk in His ways and may appreciate the acts of kindness that we do for others that gives the שכל the edge in this battle. Humility is the key in every situation and without Hashem's love and direction, we would not succeed. It is even written that Rabbi Akiva could also have fallen with the other three rabbis that entered the Pardes. Only because of Hashem's mercy, was he able to come out unscathed.