A non-therapeutic method of operating a lower extremity exoskeleton to walk, said lower extremity exoskeleton having: two leg supports (101,102) configured to rest on the ground during their stance phases where each said leg support comprises a leg rotation joint (127,128) configured to allow rotation of said leg support, a thigh link (103,104) and a shank link (105,106), wherein each said leg support further comprises an exoskeleton foot (139, 140) configured to be compliantly coupled to respective said person's foot and compliantly coupled to respective said shank link to allow the transfer of forces from said shank link to the ground; two knee joints (107,108), each configured to allow flexion and extension between respective shank link and respective thigh link; and an exoskeleton trunk rotatably connectable to said thigh links of said leg supports allowing for the flexion and extension between said leg supports and said exoskeleton trunk; said method comprising: coupling a person's leg to one of said two leg supports; coupling said person's upper body to said exoskeleton trunk; and allowing the flexion of said respective knee joints during swing phase, and resisting flexion of said respective knee joints during stance phase to allow the transfer of a force to ground; wherein the entire energy required for said flexion and extension between the shank link and the respective thigh link of a leg support over a cyclic knee motion is provided by said person. two leg supports (101,102) configured to rest on the ground during their stance phases where each said leg support comprises a leg rotation joint (127,128) configured to allow rotation of said leg support, a thigh link (103,104) and a shank link (105,106), wherein each said leg support further comprises an exoskeleton foot (139, 140) configured to be compliantly coupled to respective said person's foot and compliantly coupled to respective said shank link to allow the transfer of forces from said shank link to the ground; two knee joints (107,108), each configured to allow flexion and extension between respective shank link and respective thigh link; and an exoskeleton trunk rotatably connectable to said thigh links of said leg supports allowing for the flexion and extension between said leg supports and said exoskeleton trunk; said method comprising: coupling a person's leg to one of said two leg supports; coupling said person's upper body to said exoskeleton trunk; and allowing the flexion of said respective knee joints during swing phase, and resisting flexion of said respective knee joints during stance phase to allow the transfer of a force to ground; wherein the entire energy required for said flexion and extension between the shank link and the respective thigh link of a leg support over a cyclic knee motion is provided by said person. coupling a person's leg to one of said two leg supports; coupling said person's upper body to said exoskeleton trunk; and allowing the flexion of said respective knee joints during swing phase, and resisting flexion of said respective knee joints during stance phase to allow the transfer of a force to ground; wherein the entire energy required for said flexion and extension between the shank link and the respective thigh link of a leg support over a cyclic knee motion is provided by said person.