I tried some 5 juggling standing on my right leg. This seemed good practice, since it stops the walking forward.
What i do is to sit like a Buddha in meditation. So, that way, the lotus position prevents you from moving forward, meanwhile it establishes your yoga mastery and state of mind. Another way is to sit split legged. In this stretched position, you exercise your flexibility like a gymnast. (if you don't know about this one, watch the film Farewell My Concubine.) If in a long session you got tired of both positions, you can switch to a kneeling position, as in Japanese sits when dinning.
Also, one of the trick i practice is actually standing on one leg, and juggle 4 balls with a hand under that leg. To be precise, for example, left leg stay up, left hand under the leg, 4 balls. Vary it by switching the right hand to be under the leg. Essentially, the hanging leg becomes a fixed branch that you flow 4 balls around to form patterns. It is easy to juggle various under the leg variations, but more difficult if you try to fixed the leg in the air and let balls go around it.
The one-leg juggling is part of my imagination of a fixated style. That is, you juggle and perform n-ball variation-juggling with your body fixed like a stone. Then, as part of the routine you raise one leg and do various under leg maneuvers, but with your posture solid and movement stable.
4 balls. Stand with your feet apart in a stable position. Twist your torso so that your shoulders are facing to the right completely. Now, throw two of the balls up toward your back. With two other balls on your hands, twist your torso to face the left side to catch the balls, while throw the two in your hands toward your back. Twist to the right to catch them. Repeat. So, in perfection, you twist your torso after each throw. Note that your feet are rooted and don't move.
When done perfectly, this would be beautiful. When you reach perfection, avoid raising your head to look at the balls in any way. This can progress to all 4 balls in the air on every torso-twist. And, professional jugglers can try this with 5 balls.
The key here is perfection. The feet and hips are rooted like stone, with perfect 180° torso twists, twisting continuously with every throw, head not raised, like a automaton.
There are perhaps thousands of people around the world who can do 5-ball half-turns. But they always do it in a cloddish way with no elegance whatsoever. And always just once, as if to say “I DID IT!”. (including the best jugglers in the world)
This trick, even with just 3 balls, when done in perfection, is of real elegance. So, if you can do 5-ball half turn, try to perfect 4-ball continuous torso-twisting half-turn. Imagine your performance being some respectable ballet or figure skating, not a geek clown trying out some dexterity feat demonstration.
3 Balls. Stand with legs apart and fixed on the ground. Juggle with one of the hand under a leg. This can be right hand under right leg, or left hand under right leg, and similarly for left leg. When fluent, one can switch hands and legs per throw. So the overall move in perfection is like balls going in and out between legs.
You need to be flexible and have stamina to pull this off. At first, the right-hand under left-leg may be difficult. You can practice by just doing it one throw then switch back to regular cascade. When you are ready, turn left, slightly bend down and squat, and do another throw. With practice, you can start to do two throws consecutively each time. Eventually continuous.