Fitness or gymnastics means a set of physical activities to improve fitness and lifestyle, for the sake of well being.
Activities can take on:
Cardiovascular training which includes endurance activities performed inside using simulator-ergometers, such as cycle ergometer (exercise bike), the simulator of stairs the treadmill, rower, etc.).
Gymnastics or aerobics, which revolves primarily around lessons choreographed to music or strength training based lightweight.
Through the use of massive weight, strength training is obviously not considered fitness.