When you play a role-playing game – you are role-playing. If you’re making decisions for your fictional character, you’re playing a role.
This may include speaking in a voice, but it doesn’t have to.
This may include considering things like “motivation” and beliefs and things like that, but it might also just be what you’d want to do if you were in the fictional situation.
When you engage in combat, you’re role-playing. When you’re negotiating with other players or NPCs, no matter if you go into detail or you abstract it with “I tell them the story” – you’re role-playing. When you decide to engage with one downtime activity over another, you’re role-playing.
There’s nothing inherently better or worse about any activity in a role-playing game than any other, outside of personal preferences and expectations. It’s all role-playing either way.