We were seized by a sudden impulse to run.
我们身不由己突然想跑.
An emotion, desire, physiological need, or similar impulse that acts as an incitement to action.
动机一种能作为诱导物而激发行为的情绪、愿望、心理需要或者类似的心理推动力
On impulse, I picked up the phone and rang my sister in Australia.
我一时心血来潮，拿起话筒就给在澳大利亚的妹妹打了个电话。
