Have you ever thought why?
Common sense says that the more you visualize, the faster you get results. It is reasonable to believe that if you keep the mental image of your goal constantly in your mind, it will materialize faster. So why are you told not to think of your goal the rest of the day?
It is not that if you hold the image constantly in your mind it cannot manifest in your life. It is not that you have to release it, because if you keep it stuck in your mind it won’t materialize.
The reason is very simple. Most people do not have control over their minds. Most people have doubts and little faith, when thinking about goals and ambitions. Their minds are inclined to negative thinking and worrying.
It is usually possible to hold the mind on a goal or desire for only a few minutes, before it starts interfering with opposite thoughts. You have most probably seen how after a few minutes of visualization, doubts and impatience rise up, which makes it difficult to concentrate and keep thinking positively. This means that if you keep thinking about your goal for too long, you will unconsciously start to sabotage all your previous positive visualization, and consequently accomplish nothing.
During the day, while engaged in various activities, the predominant mental attitude rules, and if it is negative, any thinking about your goal will be negative too. Only if you are well trained in concentration, and positive thinking became a habit with you, it will be possible for you to think positively about your goals, at any time of the day.
There is another reason why it is advisable to let go. Visualization activates your subconscious mind, which consequently sharpens your intuition, brings you useful ideas concerning your goals, and inspires and motivates you to achieve them.
By releasing the mental image, you free your conscious mind to become aware of the prompting of the subconscious mind. You make it possible for the subconscious mind to bring important information to your conscious mind. This action makes you become more aware of opportunities that pop up, and let the subconscious mind motivate you to take action, instead of just waiting for things to happen.