But sometimes—whether it’s running a marathon, climbing a mountain, or assembling furniture—we willingly choose difficulty over ease. Michael Inzlicht, a psychologist at the University of Toronto, calls this the effort paradox. While we often eschew hard work, other times we value it, viewing things as more rewarding if we have to work for them. We hike mountains even though we could see the same view by gondola and willingly spend more on furniture we put together than on preassembled pieces. “Both things seem to exist at once: we avoid effort, we also seem to like it,” says Inzlicht.