There are sects (like the ultra orthodox) who don't use Sabbath mode specifically for this reason. They say that the added weight causes the elevator's motor to work harder thereby desecrating the Sabbath.
Also, depending on the counterweight and the current load of the elevator, adding an extra person to it might tax the motor less even when ascending.
The prohibition is not work, but rather creation. In this case creating electrical energy.
The only way I can think of to completely avoid creating anything would be to remain unconscious the entire time, thus preventing yourself from making any choices.