So if you are being disturbed when praying or studying Torah, by a person or any other way, take it as being for your good -- that you were not concentrating properly, and so heaven sent you this disturbance to make you aware that you should strengthen your kavvanah [sincerity, intention, direction of the heart]. (Keter Shem Tov)

The Baal Shem Tov in Jewish Spiritual Practices by Yitzhak Buxbaum