St. Diodochos of Photiki explains another important principal for those who tend to be very zealous:

“It is in no way contrary to the principles of true knowledge to eat and drink from all that is set before you, giving thanks to God; for “everything is very good” (cf. Gen I.31). But gladly to abstain from eating too pleasurably or too much shows great discrimination and understanding. However, we shall not gladly detach ourselves from the pleasures of this life unless we have fully and consciously tasted the sweetness of God.”

Notice how St. Diodochos says “gladly” to abstain and detach ourselves. This is key: we only can gladly abstain when we’ve tasted something better, “the sweetness of God.” It’s difficult to exercise self-control in the right spirit if we have not experienced the sweetness of God, or if we have forgotten our “first love” (Rev 2.4). But it’s common for those tempted by zealousness to try to jump to the top of the ladder right away, rather than going up one step at a time, to use the image of St. Dorotheos. They see that something is better, and assume they must accomplish it right away.

Glory and Honor: Orthodox Christian Resources on Marriage