How do I Tween an instance variable?

Trying to use the the tween behaviour to to tween a variable but there is no way to tell it what variable I want to tween!?

Tween (value), set up your tween parameters.

Then, every tick -> set object variable to object.tween.value

Tween (value), set up your tween parameters.

Then, every tick -> set object variable to object.tween.value

Thanks! Worked like a charm :)