Metaphor: metaphor means that “it” parallels other activities in life.
“Juggling, focus and concentration, parallels other activities in life that need, use, or demand mental focus.” - Sir Drop-A-Lot
Juggling builds on focus and concentration. So, for any activity that needs focus and concentration, juggling will be a great parallel activity. Juggling will help train, activate, and refresh the mental outlook needed for focus and concentration.
Juggling, learning to learn to juggle, or practicing juggling, its 4 components: focus, concentration, knowledge, and understanding seems to mimic and relate quite nicely to the 4 pillars of Zen, Buddhist mindfulness: the body action, feeling, mind and mental outlook. So juggling can benefit and assist where mindfulness applies.
So “Juggling” can be used in parallel with any activity requiring “Mindfulness.”