Periodic cellular structures are widely used for engineering applications due to their lightweight, space filling, and load supporting nature. However, the configuration of the cellular structures is generally fixed after they are initially built, and it is extremely difficult to change their structural properties -- particularly their load bearing capabilities -- in a controllable fashion. Here, we show that volumetric origami cells made of Tachi-Miura Polyhedron (TMP) can exhibit in-situ transition between flat-foldable and load-bearing states without modifying their predefined crease patterns or hitting the kinematically singular configuration. We theoretically study this mechanical bifurcation to establish our design principle, and verify this experimentally by fabricating self-folding TMP prototypes made of paper sheets and heat-shrinking films. We demonstrate the improvement of load carrying capabilities by \(10^2\) by switching the TMP from foldable to load-bearing configurations. These reprogrammable structures can provide practical solutions in various engineering applications, such as deployable space structures, portable architectures for disaster relief, reconfigurable packing materials, and medical devices like stents.