Detachment in breathing meditation

I read this answer, and it made me wonder something deeply; the answer seemed to imply strenuous or volitional attention was inferior to watching the mind for breath meditation, and that merely observing was more effective. I have heard such a statement many times elsewhere, that too much 'expecting' or 'grasping' inhibits concentration. **If this is so, how does a practitioner loosen their grip on the mind? How does one observe the breath with detachment?**