Dear friends, to maintain potency and vigour is not too easy, the sexual functions are mainly determined by pituitary hormones, called gonadotrophins and local hormones produced by gonads, in males and fsh in females, so its totally hormone based chemistry, but the flow of hormones is not consistent, pituitary flow depends in excessive or lack of local gonads hormones, but we cant maintain it through injection of hormones or drugs, it is too depends on nervous condition of the person, psychological stares of brain and different-2 stimulus, effects it, suppose if you see a charming beautiful, thing, suppose a girl or a flower, you get pleased, but if you see in place of it any ugly thing, what happens to you, suppose if you are traveling, and you are a good traveler, and if any person sitting near you starts, vomit, if vomit in your seat, how you will react, so its called a psychological state, & its role in sexual behavior is very effective and prominent, i can talk too much privately to you, if you can message me, i can discuss each issue, nicely and provide tips separately, my subject is medical astrology, treatment with effective measures, but i need few details, so i can effectively guide the requiring person.