How difficult is it to stand on one leg?
Pretty easy as you get older because you know where to put your weight, right? Young kids find it difficult because they don't understand that they have to put all their weight on the one foot.
How difficult is it to stand on one leg, on tiptoe?
Bloody difficult! I feel like a young kid again, falling everywhere. It was only until yesterday that I really thought about the physics (?) of it. If you put all your weight on the one foot when standing on one leg normally, you can stay like that for a long, long time. So it only makes sense that when you go up on tiptoe, you have to put all your weight on the front of your foot! So why. can't. I. grasp. that?
Can you imagine me standing in the middle of my apartment tiptoeing on one foot, arms outstretched, as if I'm a Shaolin monk? Well, you don't have to now. Just use a telephoto lens. And sell the pics of me falling all over to the papparazzi :P