Waiting is a state of mind. Basically, it means that you want the future; you don't want the present. You don't want what you've got, and you want what you haven't got. With every kind of waiting, you unconsciously create inner conflict between your here and now, where you don't want to be, and the projected future, where you want to be. This greatly reduces the quality of your life by making you lose the present.
Eckhart Tolle (2010). “The Power of Now: A Guide to Spiritual Enlightenment”, p.86, New World Library