To say the quiet part out loud: your body's center of mass is located near your belly button. [0] You maintain balance through a combination of your vision, vestibular system, and proprioception [1]—focusing attention on your belly button keys into that last method and reinforces your overall sense of balance.

[0] https://www.professionalptandtraining.com/balance-strategy-b...

[1] https://www.neurolab360.com/blog/balance-and-proprioception

Attention. Concentrate on your belly button.