Sporty seniors looking for an activity that won’t result in dislocated hips might want to consider taking up the historic sport of billiards. (It originated in 18th century France.) The San Francisco Billiard Academy will teach you basics such as stance, aim, stop/follow/draw, side spin and strategies. They offer 8-ball and 9-ball clinics and if you are already fairly skilled, courses to become a certified billiard instructor. $75 for a four-hour course at the location of your choice.