The human body usually produces a wide range of compounds each of which has a unique function. Testosterone is one of those compounds. While both men and women have testosterone, the concentration of the hormone in the male body is higher than the concentration in women. This is because the hormone is largely a male sex hormone. Production of the hormone usually starts at puberty, peaks in the late teens and starts to decline at around the age of 30 years. This is usually when start to lose their youthful vigor.
When t-levels start declining, therapy is highly recommended. This is meant to restore t-levels to normal levels. There are many qualified medical practitioners who can administer testosterone replacement drugs. It is important to note that these drugs are highly regulated to avoid abuse by athletes and some misguided youths.