There are a number of reasons that exercise has an effect on the brain, according to Santosh Kesari, MD, PhD, neurologist and neuroscientist at Providence Saint John’s Health Center in California.

“Aerobic exercise helps with vascular integrity, which means that it improves blood flow and function, and that includes the brain,” Dr. Kesari notes. "That's one of the reasons that being sedentary increases your risk of cognitive issues because you're not getting optimal circulation to the parts of the brain related to functions like memory."

He adds that exercise also can stimulate the growth of new connections in the brain, as well as reduce inflammation throughout the body. Both play a role in helping lower age-related brain health risks.

A study in Preventive Medicine found that cognitive decline is almost twice as common among adults who are inactive, compared to those who get some form of physical activity. The connection is so strong that researchers recommended the encouragement of physical activity as a public health measure for reducing dementia and Alzheimer's disease.

Although there is ample research noting that endurance training and strength training are beneficial for older adults, those who are just starting to exercise may feel less overwhelmed by recognizing that all movement is helpful.

For example, in its information about older adults and brain health, the Centers for Disease Control and Prevention (CDC) suggests activities such as dancing, walking, light yard work, gardening, and using the stairs instead of the elevator.

It also recommends doing quick activities like squats or marching in place while watching TV. To keep increasing exercise and finding new ways to challenge yourself every week, the CDC recommends keeping a simple diary of daily activities.