How to Generate Idle Avatar Video Without Speech Using /v2/video/generate API

Hello HeyGen Team,
I would like to know how to create an avatar video that shows the avatar in an idle position without any talking or lip movement, using the https://api.heygen.com/v2/video/generate API.

I have successfully used the API to generate talking avatar videos using script input, but now I want to generate a silent video — for example, the avatar should just be in a natural idle pose (perhaps blinking or making small movements), without delivering any script or voiceover.