About This Answer
When Luang Pu Mun began meditating and his mind lacked samādhi, Ajahn Dtun recounts, he held on to Buddho and did not let it go, keeping mindfulness with it as much as he could until concentration arose. At the start, a meditation word or object is needed to train mindfulness to stay in the present. Without the breath or Buddho, mindfulness drifts off with thoughts of the past, imaginings about the future and all kinds of restlessness, because the mind has no foundation to rest on.
As a teenager before ordaining, he says, when foolish, restless thoughts came up and he lacked the wisdom to let them go, he simply brought mindfulness back to the breath and ignored the thought. After two or three minutes the unwholesome thoughts had gone and the mind was in the present. He saw then that mindfulness could take charge of the mind, so that one thinks, speaks and acts only in good ways.
If mindfulness and wisdom are not watching over the mind, greed, anger and delusion take control, leading to unwholesome thought, speech and action that bring suffering. That is why we must keep driving the defilements out of the mind.