As soon as we begin trying to practise mindfulness of breathing or any other type of meditation, we notice the presence of intrusive thoughts. The Buddha identified these thoughts and the emotions that often accompany them as being of five main types Ý sense desire (kàmacchanda), ill-will (vyàpàda), sloth and torpor (thãnamiddha), restlessness and worry (uddhaccakukkucca) and doubt (vicikicchà). These five hindrances are not just disruptive to meditation, they are also the root cause of most psychological problems as well, and thus coming to terms with them can be to our mundane and our spiritual advantage (A.III,63).
The Buddha said that these hindrances `cause blindness, lack of vision and contribute to distress' (S.V.111). He also said that when they are diminished, the mind becomes `malleable, pliable, workable and bright' (S.V.92) and that being free from them, even temporarily, allows `gladness to arise, from gladness comes joy, being joyful the body is stilled, a still body creates happiness and the mind that is happy becomes concentrated.'(D.I,73).The intrusion of the hindering thoughts during meditation can be weakened and in the Vitakkasaõñhàna Sutta the Buddha recommends several ways of doing this Ý replacing agitating thoughts with neutral ones, considering the disadvantages of such thoughts, ignoring them and forcefully cutting them off, etc. (M.I,119ff).
However, the hindrances are nourished by our behaviour when we are not meditating and so the best way to deal with them is by bringing about changes in our lifestyle. Following the Precepts, not deliberately seeking out excessive sense stimulation, being patient with oneself and spending time in silence, can all help achieve this. The subsiding of the five hindrances opens the way of the jhànas. See Progress in Meditation and Sleep.