An activating platform is disclosed. The platform includes a curved support plate. The support plate is divided into a standing area and a sitting area, the sitting area including a chair with a mounting arrangement and a seat. The curved shape of the support plate is meant to provoke the balance of a user standing or sitting on the platform, i.e. that the user has to use the muscles actively to hold the balance. Naturally, the user will rock around in a small angle around a middle position and flex in the hips and back to maintain the balance.