The acronym "F.I.T.T." stands for Frequency, Intensity, Time, and Type in exercise programming. This principle serves as a guideline for developing effective workout plans. Frequency refers to how often you exercise, Intensity indicates how hard you work during the session, Time denotes how long you exercise, and Type refers to the kind of exercise performed. By manipulating these variables, individuals can tailor their fitness programs to meet specific goals, such as improving strength, endurance, or flexibility.