Exercise is good for people of any age. It can help make you stronger, prevent bone loss, improve balance and coordination, lift your mood, boost your memory, and ease the symptoms of many chronic conditions.
A lot of the symptoms that we associate with aging -- such as weakness and loss of balance, are actually symptoms of inactivity, not age.
In fact, some people in their 70's, 80's, and 90's are out there running marathons and becoming body-builders. As previously mentioned exercise improves more than your physical health. It can also boost memory and help prevent dementia. It can also help you maintain your independence and your way of life. If you stay strong and agile as you age, you'll be more able to keep doing the things you enjoy and less likely to need help.