... days.b). as long as you wish, if the balls are used out of the sun or at night ... .c.) just change the air inside the ball at least every 30 minutes3), HOW DO YOU ... GET INSIDE OF THOSE BALLS?We have a zipper!4), HOW DO I BLOW THEM UP ... balance, endurance, and its fun, but if you need a work out walking and controlling the water ball can be ...