Yes, having a belief can have the side effect of changing your behavior independently of how you would consciously change your behavior in light of your beliefs.
When you have an accurate belief, and the side effects of believing it affect your behavior in a way you consciously believe is positive, then take advantage of it! If you can get a boost toward your goals without making a conscious effort, then by all means cut out conscious effort as the middleman in the causal chain between your beliefs and your goal state.
But if you spy a shortcut between an inaccurate belief state and your current goal, don’t follow the causal chain from the beginning, but meet it in the middle. Strive to shape your behavior according to your prediction of its effect, but leave your innermost beliefs to entangle with reality. They are shaped too much by non-entanglement processes as it is.
Regarding self-fulfilling beliefs:
Yes, having a belief can have the side effect of changing your behavior independently of how you would consciously change your behavior in light of your beliefs.
When you have an accurate belief, and the side effects of believing it affect your behavior in a way you consciously believe is positive, then take advantage of it! If you can get a boost toward your goals without making a conscious effort, then by all means cut out conscious effort as the middleman in the causal chain between your beliefs and your goal state.
But if you spy a shortcut between an inaccurate belief state and your current goal, don’t follow the causal chain from the beginning, but meet it in the middle. Strive to shape your behavior according to your prediction of its effect, but leave your innermost beliefs to entangle with reality. They are shaped too much by non-entanglement processes as it is.