But the good news is that increasing levels of physical activity brings health benefits to all age groups, and you don't have to jump into a massive lifestyle change. Inactive people should start with small amounts of physical activity and gradually increase duration, frequency and intensity over time.

WHO defines physical activity as any bodily movement produced by skeletal muscles that requires energy expenditure – including activities undertaken while working, playing, carrying out household chores, traveling and recreational fun.

Most health experts state that exercise is one of the best ways to be more active across the board, a key to well being.

Physical exercise is defined as “any bodily activity that enhances or maintains physical fitness and overall health and wellness. It is performed for various reasons, including strengthening muscles and the cardiovascular system, honing athletic skills, weight loss or maintenance, and merely enjoyment.”

The key here can be the sheer enjoyment, making exercise fun.

TIP: Pick an exercise you like, an activity you enjoy -- walking, bike riding, swimming -- whatever works for you.

Sports icon Billie Jean King is a President's Council on Fitness, Sports & Nutrition Council member who has spoken on the mental health benefits of exercise, and life lessons it can teach you. “I use the lessons that I learned as a young athlete every day. How to adapt to things, how to handle pressure, and how to persevere and keep bouncing back.”