"Stepped it" is an idiomatic phrase that means to increase one's activity or effort level. Some antonyms for this phrase could include "slacked off," "decreased effort," "took it easy," or "scaled back." These opposite expressions reflect a decrease or reduction in activity, energy, or commitment. Using antonyms for "stepped it" can describe a situation where someone is not as motivated or engaged, or where there is a reduced level of intensity or urgency. Both the original phrase and its antonyms can be used in a variety of contexts, such as work, exercise, or personal relationships, to convey the level of effort or involvement.