NOVELTY - The device has a movable element (1) i.e. treadmill, for a user to perform exercise, and a support frame (2) mounted on an end of the movable element and including a supporting portion arranged on a top end of the movable element. A loop-shaped frame part is mounted on the supporting portion. A work platform (4) is used for the user to work and formed on the frame part. The work platform includes a fixing board mounted to the work platform. The fixing board extends the work platform toward the user. A control assembly (5) is coupled to the fixing board for controlling the movable element.    USE - Exercise device.    ADVANTAGE - The work platform is firmly mounted on the support frame by the frame to prevent deformation or damages and mounted on the frame, so that the work platform has better support from the frame when the frame is formed in loop shape with an appropriate area. The frame includes two handrails that can swing sideways under the work platform, so that the user can rotate the handrails out of the work platform, and the user can hold the handrails while exercising. The device uses an operating interface to control the movable element, so that the user can use software to expand exercise modes or replace the software by one with different functions through a computer device i.e. desktop computer, and a control unit so as to allow a user to enjoy more exercise modes and maintain interest and habit of exercise. The device includes documents to be placed on the work platform for convenience of the user when the user needs to work while running on the movable element. The user can use the computer device for word processing and web browsing, or purely enjoying music while exercising. The movable element uses as a crank rotating mechanism, so that the user can perform a cycling exercise to achieve same effects.    DETAILED DESCRIPTION - The movable element is a running platform or a crank rotating mechanism. The supporting portion is a board bent into an L-shape or U-shape for supporting the frame. An INDEPENDENT CLAIM is also included for a system for working and performing exercise.    DESCRIPTION OF DRAWING(S) - The drawing shows a perspective view of a device for working and performing exercise.    Movable element (1)    Support frame (2)    Work platform (4)    Control assembly (5)    Computer device (6)