Antonyms for the word "more zestful" include: dull, lifeless, boring, tedious, unexciting, and uninspiring. These words describe a state of being that is lacking in energy, enthusiasm, and vigor. If someone is not feeling zestful, they may seem lethargic or disinterested in activities that they would normally enjoy. It is important to identify and address the causes of a lack of zest, as it can have negative impacts on mental and physical health. Finding ways to increase one's zest, such as trying new activities or spending time with friends, can lead to a more fulfilling and enjoyable life.