To-do lists are ineffective because they lack context: Research shows people leave the most difficult tasks undone at the end of the day. Instead, Markovitz advises laying out blocks of time for each task. "I tell people to have a healthy relationship with their calendars," he says. "How can you prioritize if you don't know how much time you have? You need to make mindful decisions about the finite amount of time you have to work." Blocking out time provides structure and gives you micro-deadlines to complete tasks. Leave a few empty spaces for inevitable crises and interruptions, and to make room for tasks that may take longer.