Genetics can significantly influence fitness by determining predispositions to physical traits, metabolism, and responsiveness to exercise. Genetic variations affect muscle fiber composition, affecting endurance and strength potential. For example, some individuals may have a genetic advantage that allows them to respond better to specific training regimens, while others may struggle despite effort. Understanding these genetic factors can help individuals tailor their fitness plans for maximum effectiveness and set realistic expectations. However, environmental factors such as lifestyle and diet also play a substantial role, highlighting the importance of a holistic approach to fitness.