Three stages in intensity of lusts and its correspondence to the three partners of birth:Man’s years are split to three:
Man’s years are split to three periods in terms of his challenges in service of G-d due to forbidden lusts and pleasures. These three periods correspond to the three partners in creation of man. The first period of a man’s life is his adolescent years in which he is challenged by strong lusts and desires. At this point, man has raging lusts for the opposite gender. This corresponds to the portion of the mother found in the person, which is responsible for the lust a man has for women. On this the verse states “Uvecheit Yechemasni Imi”, as the lust for the sin came as a result of the mother’s portion. A woman on the other hand contains a lust for men due to the portion of the father found in her. The second period of man’s life corresponds to the father’s portion found in him, while the mother’s portion is already dissipated. This is why middle aged men have a decreased lust, in comparison to that which they experienced in their adolescent and early twenties. Nonetheless, the father’s portion does leave him with some lust, although more controlled. [Perhaps this explains why men reach their peak of lustfulness during adolescence while women end to reach it only when they are middle age, as the father’s portion is only expressed during middle ages, and it is the father’s potion that creates the lust of a woman.] The third period of one’s life is when he comes old, and loses all lusts completely. This period corresponds to Hashem’s portion in the person. From all the above its understand that for a man to subjugate forbidden lusts in his elderly years is no novelty, and subjugating them in his adolescence and early years is greater than doing so in his later years.
 Or Torah [Maagid] Mishpatim 100