Maintaining strength as you get older is not for the weak-at-heart, but it will help you stay young-at-heart.
Our bodies are designed to move, as we get older this could be more of a challenge. Part of this challenge is maintaining your strength to preserve your muscles. Your bones may also lose some density, strength training is one of the best defense against this loss of bone. Balance is also affected as part of the aging process. Losing your balance makes it easier to fall and in some cases can be fatal.
Muscle building exercises such as leg press, squats, leg extensions, leg curls and calf raises will go a long way in helping preserve muscles and bones plus the prevention of falls.
It is also a good idea to practice one leg exercises such as some Yoga exercises. Other exercises should also include Tai-Chi and Water Aerobics would also be very helpful.
In the video below you will see a dumbell squat exerise demonstrated by a regular exerciser over the age of 80.