Not so long ago, a century or two, farmers would always leave one of their fields fallow. They would give that piece of their land a rest, so that it would be more fruitful in future harvests. We, however, work our fields without ceasing all through the living day. There's nothing wrong with being productive — we all know it can give a profoundly satisfying sense of achievement — but if we never let ourselves do nothing at times, our inner resources will drain away, and we shall move through our days with a pervading sense of unease. We shall not, in short, be happy.

Roger Housden in Seven Sins for a Life Worth Living