The most basic principle in physical activity that indicates doing more than normal for improvement to happen is called the Overload Principle. This principle states that in order to improve fitness or physical performance, the body must be stressed by working harder than it is normally accustomed to. By doing more than the usual amount—whether through increased intensity, duration, frequency, or type of exercise—the body adapts and improves. The Overload Principle is fundamental because without applying greater-than-normal stress, no improvement occurs. It is often implemented via the FITT model, which stands for Frequency (how often), Intensity (how hard), Time (how long), and Type (kind of exercise). Other related principles include:

• Progression : Gradually increasing the overload to continue improving.
• Specificity : Tailoring the exercise to specific goals or body parts.

However, the key starting point for any improvement is the Overload Principle—doing more than normal to induce positive adaptation.