I think 15 years is too long for a goal - think in terms of goals for today, for this week, for this month, for this year. Even Strategic plans for companies only go out 5 years and they are re-evaluated every year.

You really can't say I want "Blank" to happen before my 30th birthday when your 30th is 15 (or what ever number) years away. It's too vague, not measurable...too easy to get off course.