Rubin says it's important to learn when to let go of a project you've started but never completed. "One very effective way to complete a project is to abandon it," Rubin wrote. While going through her family's toy closet, she found a kit for building a model of a mountain that she and her daughter had bought, but then opened to find that the directions were difficult to understand. "There it had sat for months, opened but untouched, a reproach," Rubin wrote. "Now, I removed the useful materials, added them to our art supplies, and threw away the box."