You can only feel good about what you're not doing when you know what you're not doing. David Allen in Ready for Anything, p. 6

What lies in our power to do, it lies in our power not to do. - Aristotle

Besides the noble art of getting things done, there is a noble art of leaving things undone. The wisdom of life consists in the elimination of nonessentials. Lin Yutang - Quoted by David Allen in Ready for Anything, p. 11

Knowing your commitments creates better choices of new ones. David Allen in Ready for Anything, p. 9