Final answer:
False The overload principle involves gradually increasing exercise demand to improve fitness, and not merely starting new activities, making the statement false.
Step-by-step explanation:
The statement "The overload principle can help you improve your fitness levels by only starting new activities" is false. The overload principle refers to the process of gradually increasing the demand.
To improve fitness levels, one must increase the intensity, frequency, or alter the type of exercise beyond the current levels. Simply starting new activities is not enough;
The principle emphasizes the need to continuously challenge the body in order to see improvements in physical fitness.