What is the antonym of lethargic?

The antonym of lethargic depends on the specific context, but some common options include:

General antonyms:

* Energetic

* Vigorous

* Active

* Lively

* Spirited

* Alert

* Animated

More specific antonyms:

* Dynamic (if referring to energy or dynamism)

* Enthusiastic (if referring to lack of enthusiasm)

* Motivated (if referring to lack of motivation)

* Alert (if referring to drowsiness or sluggishness)

The best antonym will depend on the specific situation and what aspect of "lethargic" you want to emphasize.