io9
Balance boards can improve your core strength, posture and (obviously) balance, and this highly rated non-slip model is just $20 today, complete with a 5-year warranty. Once you’ve mastered standing on it, try adding in juggling.
https://kinjadeals.theinventory.com/this-22-balance-board-is-a-great-way-to-strengthen-you-1790754552