Post back surgery I had to do core and back strengthening and balance exercises. Standing on one leg, keeping my back straight, pivoting at the hips to pick up a water bottle or basketball, then stand up straight again, and repeating the action 10 times whilst staying on one leg, picking the thing up, and putting it back down. I felt like I was a 3-year old with how poor my balance was. It also made my feet hurt like a child made to walk to the shops.
Just tried the exercise again now after not doing it for a long time. Yep, still terrible. I actually thought it would be much easier since I do inline skating regularly, and can roll on one skate for a decent while even down to pretty low speeds. More to add to the regular fitness routine...
When I remember, whilst brushing my teeth, I'll stand on one foot for 30 seconds at a time. It's also surprisingly hard and tiring.