Push-ups/Sit-ups/Squats are 3 great exercies anyone can do! These exercies can be modified to the current activity level of each person performing the exercise. I used to do 100 reps of each one of these exercises a day. To answear your other question, the benefits of strength training are increased muscularity, which helps prevent injury. Also you will develop more lean body mass, the more lean body mass you have the better your body functions.
