Goals Set the Direction Not the Outcome
While it is important to have visualizations and goals, it is also important to avoid becoming too attached to the actual outcome, to the exact details of the visualization or the goal. Instead, the primary purpose of setting goals is to define a direction. Become attached to the direction and feeling of the goal - the essence of what you want to do - and go in that general direction. Keep your eyes open to opportunities that will come along the way and adapt or make adjustments accordingly.
It is impossible to predict the future and to plan out a path that you follow exactly down to the last detail. If life unfolds exactly as you planned and expected when you were younger, you may not be taking enough risks or aiming high enough. It is more important to know the general direction that feels right early on and figure out the details as you go along. Adjust your direction along the way as you experience the unknown and update what you know.
For example, in their first year of university, students will have an idea of the kind of career that they want and pursue that as a goal. However, choosing a career in high school or university assumes that they know everything there is to know about themselves and about the world that they are entering with their career, which is impossible. Often, by their last year of university, students do not end up where they had originally planned.
For many, it can be a significant blow to their identity and goals that they worked so hard to try to achieve. Instead, it is better to aim in the general direction of what they want to do (e.g. if they like science versus the arts), and adapt to the chaos of the world as it unfolds, adjusting their direction as they learn more about themselves and the world, avoiding attachment to any particular outcome. This process of letting the chaos of the world change them for the better is more valuable than achieving exactly what was planned, or forcing themselves to stay on a predetermined path.
It is important to set the right direction early on. It will be more difficult as time goes on to make big changes in direction rather than small adjustments (e.g. switching from science to the arts or vice versa). However, once you determine the right direction, the details aren't as important. The goal should be general enough to provide direction but not be so general that it is meaningless. Focus on the core essence of what you want instead of the details.