Exercise is physical activity with the goal of improving physical fitness.

The correct answer for: is: Exercise is physical activity with the goal of improving physical fitness. True.

Explanation:

First of all exercise concept defines it as the physical activity developed to maintain physiological well being. So this is true, but let's analyze the reason backing it. On the first hand, there are a lot of physical activities we can perform, but not all of them are focused to improve our health. Most of them are focused on different objectives but the only exercise is planned to get healthier. Just picture the case of people with obesity, they perform certain routines to improve their health in medium-short term goals. But it doesn't mean their routines aren't planned. That just means their goal is planned in a larger term than short time results.  

proteins is the answer