By fixating on an expectation or even on something like a trip or event, not only do we give away the ability to fully appreciate all the time between then and now, but it is as if we tell ourselves that our happiness depends on getting what we want or on being somewhere other then where we actually are. Our attitude changes, our way of relating to others changes. The quality of our lives and of those around us drops.
Its not that having hopes, goals or exciting plans are bad things, its that being too attached to them causes suffering. If we cling too tightly to what we think SHOULD BE happening, we are disconnected from what IS ACTUALLY happening. This causes us suffering. If we have hopes, but remain open to what unfolds, we will be much happier, much more present and able to maintain inner peace through the changes life inevitably brings.
If we are not so attatched to our preferences, our likes and dislikes (raga and dresha in Sanskrit), then we are free to receive and enjoy what comes. If we let go of struggling for the goal, we effortlessly come into harmony with life itself and feel that the journey is the goal, that each moment is the goal.