"Be careful what you wish for" is generally associated with negative events, but it also applies to positive ones, like goals and aspirations.
We place a high value on what is 'real', yet we allow ourselves to be guided by imagination. We are guided more by illusion than by 'truth'.
Many people delay their progress because their vision is simply an unattainable grand design. Wishing and hoping won't do it, unless you believe it.