Moses told the Jewish people,"You will return to G-d with all your heart and with all your soul."
Whereas we are here commanded to return to G-d with all our heart and soul, we have been commanded previously to love G-d not only with all our heart and soul, but with "all our might." What is the reason for this difference?
Loving G-d "with all our might" means being devoted to Him beyond what we consider "normal," i.e., beyond what makes sense logically.
Repentance, on the other hand, requires that we forge a stronger relationship with G-d than our present one. That relationship with G-d, after all, was too weak to keep us from wrongdoing and therefore from needing to repent. We therefore need to deepen our feelings toward G-d, in order for Him to mean more to us than the indulgences that we have learned to rationalize.
Thus, whereas the Torah bids us to love G-d beyond what seems "normal," it bids us to repent by making what used to be "beyond" us into our new "normal." The processes associated with repentance and love are directly opposite, the first taking us beyond our innate limitations and the second bringing transcendence into limited consciousness.