Wikipedia puts the "preferred walking speed" around 3 miles per hour, so that would be 2 hours of walking per day. So with 8 hours of sleep, 8 hours of work, 2 hours of walking, 1 hour of hygiene, 1 hour of commuting, and 2 hours for meals, you'd still be left with 2 hours of personal time to do all your extracurriculars like cleaning, parenting, spousing, hobbying, shopping, repairing things, etc.