A foldable user-support device configurable to be positioned on a ground surface comprising: (a) a seat having a main, rearward seat portion and an auxiliary forward seat portion and manipulable between the following three positions: i) a lower rearward seating position, in which the main seat portion and the auxiliary seat portion are disposed adjacent each other and aligned to provide a pre-determined seating length along a horizontal plane; ii) an elevated seating position, in which the main seat portion maintains its orientation when the seat is moved from the lower rearward seating, and at least a majority of the auxiliary seat portion is lower relative to the main seat portion, and is oriented transversely thereto whereby the seating length of the seat is reduced; and iii) a folded position, in which the main seat portion and the auxiliary seat portion change their orientation relative to that in the lower seating position, and a length of their total projection on the horizontal plane is smaller than the reduced seating length of the seat in the elevated seating position; and (b) a seat manipulation and folding mechanism (100, 700) configured to move the seat between the lower rearward seating position and the elevated seating position and between the elevated seating position and the folded position. (a) a seat having a main, rearward seat portion and an auxiliary forward seat portion and manipulable between the following three positions: i) a lower rearward seating position, in which the main seat portion and the auxiliary seat portion are disposed adjacent each other and aligned to provide a pre-determined seating length along a horizontal plane; ii) an elevated seating position, in which the main seat portion maintains its orientation when the seat is moved from the lower rearward seating, and at least a majority of the auxiliary seat portion is lower relative to the main seat portion, and is oriented transversely thereto whereby the seating length of the seat is reduced; and iii) a folded position, in which the main seat portion and the auxiliary seat portion change their orientation relative to that in the lower seating position, and a length of their total projection on the horizontal plane is smaller than the reduced seating length of the seat in the elevated seating position; and i) a lower rearward seating position, in which the main seat portion and the auxiliary seat portion are disposed adjacent each other and aligned to provide a pre-determined seating length along a horizontal plane; ii) an elevated seating position, in which the main seat portion maintains its orientation when the seat is moved from the lower rearward seating, and at least a majority of the auxiliary seat portion is lower relative to the main seat portion, and is oriented transversely thereto whereby the seating length of the seat is reduced; and iii) a folded position, in which the main seat portion and the auxiliary seat portion change their orientation relative to that in the lower seating position, and a length of their total projection on the horizontal plane is smaller than the reduced seating length of the seat in the elevated seating position; and (b) a seat manipulation and folding mechanism (100, 700) configured to move the seat between the lower rearward seating position and the elevated seating position and between the elevated seating position and the folded position.