In scuba diving, “buoyancy control” refers (generally) to the skill of maintaining “neutral buoyancy” while underwater. That is, through regulating your breath, you keep an internal density that’s equal to the density of the water around you. Meaning, it’s your ability to float while immersed, rather than getting pushed around by the always changing currents.
When we’re feeling balanced in our lives, we are experiencing the all-around sense that we get physically when we’re amongst the kelp. Things are happening, changes are occurring, the boss did that thing again, and Uncle Harry has the politics of 1955, but we don’t internally feel upset, thrown, or imbalanced. We’re buoyant. It has the qualities of feeling grounded, often pleasant, but primarily safe and under control (without being overly controlling).