The answer to this question depends on what you really mean. If you are merely wishing something or if you are wishing something you absolutely know is impossible, then you say, “I wish I were in Paris.” But, if you believe there might be a way you just haven’t hit on it yet, then you say, “If there was a way to get to Paris, I’d find it.” The first is in the vein of wishful thinking, and the second is not.