Testosterone therapy, also known as testosterone replacement therapy (TRT), is a medical treatment that involves supplementing the body with exogenous testosterone to raise testosterone levels. It is typically used for individuals who have low testosterone levels and are experiencing symptoms such as low energy, decreased libido, muscle loss, and mood changes. TRT can be administered through various methods, including injections, creams, or pellets. It's important to work with a knowledgeable doctor who can monitor hormone levels and find the right balance for optimal results. TRT has been shown to have positive effects on longevity, mobility, cognition, insulin sensitivity, and overall well-being. However, it's crucial to note that TRT should be approached responsibly and under the guidance of a qualified healthcare professional.