Following are some general balance exercises:
These are fairly high level; not for the frail!
Seated: on a ball marching, or marching with arm movement.
Standing: Try heel to toe as shown. Try each foot in front. Try to hold it 30 seconds.
Above are several examples of balance challenges on an unusual surface. This builds stability in the lower leg, and balance reactions.
The above is called “limits of stability” Stand with your back to the corner, and a solid object you can grab in front of you. Keeping feet in place, slowly sway forward as far and you can while keeping your balance. Then sway backward as far as you can. The object is to challenge your lower legs to maintain your balance without moving your feet as your body moves.