Wondrous item rare (requires attunement)
This looks like a mundane coffee mug. It has 3 charges. When you drink any warm liquid from this coffee mug, you may expend 1 charge to remove one level of exhaustion from yourself. The coffee mug regains all expended charges daily at dawn.
Curse. The coffee mug is cursed. Attuning to it curses you until you are targeted by the remove curse spell or similar magic. Each day if you do not drink from the coffee mug you gain one level of exhaustion.
https://dmdave.com/coffee-mug-of-rejuvenation-magic-item/