It's not that
hard, really. You can learn in half an hour if you have the right teacher. And don't give me that "I'm not
co-ordinated" crap. If you can walk, you can juggle.
Get three round things that won't roll or scurry away when you drop them. Oranges are great if you don't want to invest in juggling beanbags.
Start with one. Throw it from one hand to the other. Try to flow with the ball -- don't just catch it and throw it, guide it. Make a little scooping motion so that the ball never stops moving. It should trace an arc like this:
^ ^
/ \ / \
| \/ |
| /\ |
A----a b----B
where A is the catching location, and "a" is the throwing location. (Same for B and "b" on the other side)
Throw on the inside, catch on the outside. This will become important later on.
Now try two. Put one ball in each hand. Throw one ball from your left (non-dominant) hand to your right (or dominant hand). When that ball reaches it's peak, throw the ball from your dominant hand to your submissive hand. If all goes well, the balls should pass each other in the air, each landing in the hand other than the one they started in. There should be a nice syncopated rhythm to it: Throw-Throw-Catch-Catch, like a 4-4 rhythm in music. If it's not working, keep trying.
One big problem here is collisions. If you aren't doing the scooping motions properly, the balls willl collide. Remember: Throw on the inside, catch on the outside. And make sure that everything happens on a two-dimensional plane -- don't try to avoid the collisons by moving closer to or further from your body. This is a very bad habit that will create problems later on.
Throw-Throw-Catch-Catch.
Once you can do this easily from both sides (ie starting with each hand), you are ready to try three. Put two balls in your right hand, one in your left, and read on.
A good way to think about it is as a series of swaps. There is always one ball in the air, and one in each hand. As the airborne ball begins to fall, you throw another ball up and catch the falling ball before it lands. This is what you learned to do with two.
This is what happens, in the inherently inadequate words I am restricted to here. You throw one ball from your right to your left. The right hand now has one ball, the left has one, and there is one airborne ball rapidly approaching the left hand. As the airborne ball reaches it's peak, you throw the ball in your left toward the right hand, and catch the first ball before it lands. Now the ball from the left is flying to the right hand, and another identical exchange occurs. Always one ball flying, and one in each hand. This can go on indefinitely. The world record is 8 hours and 45 minutes.
Now try it.
Yes, this is going to take a bit of practice. But you'll get it eventually.
Once you've learned how to do three, you might want to learn some tricks or move on to four ball juggling or five ball juggling.