* Lazily is the most direct adverb form, but it's often used in a more literal sense (e.g., "He sat lazily in the sun").
* Idly can be used to convey a sense of laziness, especially when it comes to mental effort or activity (e.g., "He idly flipped through a magazine").
* Slothfully implies a more extreme or deliberate laziness (e.g., "The slothful student barely cracked open the book").
* Indolently is another option, suggesting a lack of energy or enthusiasm (e.g., "She stretched out indolently on the couch").
The best choice depends on the specific context and the nuance you want to convey.