Well, the first thing is to evaluate, as objectively as possible, and with the counsel of others, whether or not the thing you want truly is or is not attainable. You might also explore why you want it so badly. Then, if you determine that it is attainable, you have to figure out what it will cost in time, effort, and money, and if it's worth it to you. If so, then set off on the journey. If not, or if you determine it is not attainable, then you have to abandon it, mourn the loss, and move on. I think most of us have a few items in that category that we miss all our lives. But too, the memories fade in time.