For aerobic exercise: Walking, dancing (when's the last time you took a ballroom-dancing class?), biking, and swimming are all good options. You can also try exercise videos. Collage Video is a good resource. They have lots of videos for individuals of all ages (search their site for "seniors"). Also check out your local senior center, rec center, Y, or local fitness center for classes that are appropriate for you. Many centers offer exercise classes for seniors. They're out there if you look.
If you have a specific skill or knowledge set that you would enjoy sharing with others, volunteer to teach a class on it! Do some research and check if you are eligible to teach, if not, tackle the requirements. Yoga, Zumba, cycling, boxing, cooking, sewing, baking, and dance classes are just a few that require minimal (if any) pre-requisites to become an instructor.
Do you feel an irresistible urge to move your legs that causes you to wake up during the night? Restless leg syndrome (RLS) is a sleep disorder that creates these feelings and can cause significant sleep disturbances. Typically caused by iron deficiency, low dopamine levels, or genetic factors RLS symptoms can be managed with exercise and stretches. Learn more about how you can implement exercises for restless leg syndrome into your daily routine.
Not only do leg raises help strengthen the thigh, hip, buttocks, and lower back muscles, this type of exercise benefits balance as well. For side leg raises, stand behind a chair and hold on for better balance. Lift one leg out to the side, keeping it completely aligned from heel to hip, while maintaining a straight back and a slight bend in the supporting leg, then slowly lower the leg. For back leg raises, use the same chair for balance and slowly lift one leg behind you (without leaning forward), hold for a moment, and lower the leg. Do not bend the lifted leg or point the toes, and keep the standing leg slightly bent. For each exercise, complete two sets of at least 10 reps for each leg, alternating legs between sets.
Importantly, strength isn't just a function of mass. It's also a function of something called "neurological patterning." In layman's terms, patterning is when the brain sends electrical signals via the nervous system to muscles to make them contract. For example, when you think about walking down the street, bending over to pick something up, or any other movement for that matter, the brain first processes the thought and figures out what muscles are needed to make the move and then sends the signal over the nerves to the particular muscles that are necessary for the movement. The muscles move (and so do you) once the signal reaches them. (See "How muscles work" for more detail.)