I just bought one too. If it's a gym ball, pull out the air plug on the ball first. Air plugs are relatively long plastic needles, similar to injection needles. Then use an ordinary bicycle to inflate it with a pump. Plug in the air plug after charging. Generally, inflation is carried out several times, five times an hour, until it is full. My pump is relatively small, and it has been pressed nearly 1000 times.

Gymnic also has a shorter plastic needle for the pump connector.