Sitting down and getting up
Try to sit only in chairs with arms, since you'll need the arms to help you lower and raise yourself in a controlled way without having to suddenly put your foot down. Avoid sitting on low couches, on soft seating that causes you to sink down, or any chair that rocks, reclines or glides.
How do you know if the height of your chair seat is correct? Back up to the chair: the seat cushion should be higher than the backs of your knees. If necessary, raise the height of your chair seat by placing a firm pillow on the seat or by putting secure blocks under the legs.