It doesn’t, of course. Architects are adept at supporting parts of bridges and buildings that project horizontally. They simply put the support where it cannot be seen. Want to build a cantilevered deck on your new house? Get 18-foot lengths of 2’X12’ lumber and place two thirds of them on edge under the weight of the house: Twelve feet of these joists will have tons of downward force, and the remaining six feet will extend into space, easily capable of holding a deck party.
In a sense we are all cantilevers. The support that keeps us from failing (or falling) is hidden in all those who helped us get where we are. For strangers, we seem to levitate, to project unsupported in space and time. In reality, that hidden support is the reason for the integrity of our life’s structure.
You, too, have probably been the hidden support for human cantilevers. You do your work in secret. No one sees you, the underlying joist mostly hidden from view. There you are, under massive pressure, bearing the weight so that another can project himself or herself freely into space and time. Feels good, doesn’t it?