A portable exercise device includes a pedal pivotably connected to a pair of supports. The pedal has a neutral position relative to a pivot axis. The pedal is configured to rotate about the pivot axis in a first direction toward one support and in a second direction, opposite the first direction, toward the other support. The exercise device also includes a resistance mechanism configured to exert a force on the pedal about the pivot axis in a direction opposite to the respective direction of rotation of the pedal about the pivot axis. The device is movable between an open, in-use configuration, where the pedal is disposed in the neutral position to receive a foot of a user and the pair of supports together form a triangular base, and a closed configuration, where the pair of supports are flush against the pedal.