Learning to juggle is like learning to ride a bicycle. Once you've got the basic move, you can't unlearn it. I can safely say I can keep three balls in the air, but only for just over a minute or so, on average, before I drop one. Here's a bit of proof:
I started learning to juggle about two or three years ago, but after a couple of weeks I stopped practicing and then have picked away at it in fits and starts. Kind of poor that this is the extent of my ability in all that time, but then, I never was a rapid study. Also, I've realized that, as with learning to ride a bike, there's this steep learning curve in the beginning and then there's this long plateau where you just can't get rid of the training wheels for what seems like eons. In terms of juggling, that seems to be the one minute mark.