The phrase "am on one's back" is often used to describe a state of physical or emotional distress, but it is not a phrase that has direct antonyms. However, there are several words and phrases that can be used to convey the opposite of this phrase. For instance, "up and about" can be used to refer to a person who is active and not incapacitated. "Standing tall" suggests that someone is confident and capable, while "sitting pretty" indicates someone is in a comfortable and advantageous position. Similarly, "on the up and up" can be used to describe someone who is making progress or recovering from an illness or injury.
