What event hasn't even happened yet, that you really want to happen? Try giving thanks for it, as if it really has happened, and see how it affects you. (It also affects the event itself.)
Being thankful by faith before an event takes places is a spiritual discipline. It doesn't take any faith or spiritual life to be thankful after an event. To live by faith, not by sight means there will be many events that are to be thankful for before they take place.