As the body ages, many changes occur that can gradually leave us more susceptible to disease and injury, and can impact our ability to function as efficiently as we once did. Although a certain degree of change is to be expected, our own lifestyle choices play a huge role in determining how quickly or slowly we experience the effects of getting older. Lack of exercise, poor eating and sleeping habits, chronic stress, smoking and excess alcohol consumption are examples of controllable lifestyle habits that contribute significantly to how well we age. How significantly does lack of exercise affect the body? Life requires us to be prepared physically fit for challenges both big and small. For much of our lives, these challenges seem very small, such as rising up from a chair, walking from one place to another, shopping for groceries, going up and down stairs, bending down to pick things up, making the bed, etc. Slightly greater challenges might include yard work, washing and waxing the car or carrying heavy grocery bags into the house. Still greater challenges might include moving heavy furniture, or climbing up a ladder to get a heavy box down from a shelf. The more physically fit you are, the more you can handle of what life throws your way. The more frequently you face physical challenges, the greater the likelihood of maintaining your strength and independence. Unfortunately, in today's world, we are required to be less and less active. We also often take for granted our physical abilities until the time comes when we find we no longer have the strength, endurance or flexibility to do the things we want to do. Driving has replaced walking, we often sit at a desk for hours on end, and then, because we are mentally drained, come home tired and stressed at the end of the day. When required to complete a task that is physically taxing, our instinct is to look for the easiest way to get it done. A few common examples: Taking an elevator instead of the stairs, using a leaf blower instead of a rake, a riding mower instead of a push mower, going through the car wash instead of washing it ourselves, or even something as simple as using an electric can opener instead of a hand-held one. Lack of daily exercise and increased stress levels are conducive to eating too many calories, adding up to weight gain and increased risk for cardiovascular disease, type 2 diabetes and many other conditions. Age-related loss of muscle mass, strength and function, known as sarcopenia, affects us all to some degree, typically beginning in the fourth decade of life with an approximate 1 percent loss per year. Thankfully, weight training is now accepted and recommended for nearly everyone -- and is especially important for older adults, helping to improve balance and overall strength and reduce incidence of falls. Proper lifting of even very light weights with elderly people has been shown to be of significant value in increasing function and quality of life. Along with weight training, many other types of exercise, including tai chi, stability ball exercises and simple balancing movements can help to improve balance and strength. Exercises that can be performed at home, such as standing on one leg or walking heel to toe are also effective. Check with your doctor for recommendations before you begin an exercise program. Frequency, duration and degree of intensity of a given exercise prescription vary from person to person. Marjie Gilliam is an International Sports Sciences Master certified personal trainer and fitness consultant. She owns Custom Fitness Personal Training Services. E-mail: marjie@ohtrainer.com. Her Web site is at www.ohtrainer.com. This article appeared in the Dayton Daily News. 