The antonyms for being wasteful with are being mindful, being economical, being frugal, being conscious, being prudent, being cautious, being efficient, being thrifty, being sensible, being wise, and being resourceful. Being mindful means being fully aware and considerate of the resources we use. Being economical and frugal aim to save and make the most of resources. Being conscious and prudent means being careful and intentional in using resources. Being efficient and thrifty aim to minimize waste and maximize utility. Being sensible and wise means making well-informed and practical decisions. Finally, being resourceful means using available resources creatively to achieve one's goals.