Listen to your gut instinct. If you can't imagine yourself being more content after achieving the goal, your vision board was just as successful as when it made you realize how much you want something. Being content does not mean you are happy, it means you are grateful and at peace. Happiness can come and go and is just a feeling. Feelings come and go and it's not humanly possible to hold onto them. Too often we strive to become happy instead of just being happy.
Your vision board can remind you that you are, in fact, content with where you are when you can't imagine yourself being in a better place after achieving a goal. Goals are often empty desires that we chase to fill our lives with a sense of purpose. A goal that does not stem from desire, but from being content, will be truly rewarding.
Once you accept where you are, you can start to let the present guide you. When you don't chase goals that are outside yourself and strive to be more in tune with your inner self, the bliss you feel stays with you. When your goal is buying a car, the novelty will wear off soon enough and you will still be the person you were before, most likely looking to fulfil a new desire. One can see how this has caused a surge in people applying for debt counselling! This is no way to live, but it is totally normal and acceptable. In fact, it is expected of us to always desire more and better things and situations in our lives.
The most powerful thing you can do is to create a mind-set for yourself where you are content with every moment as it comes. A vision board can help. Let the images you gather guide you towards being content with your life as it is. Collect images that remind you of things, people, places, experiences and so forth that have made you the person that you are. It's like counting your blessings or taking stock of where you are.