In the great cycle of the world's pulse, its flow of spiritual life, Israel's task is to act as a vital center, as a heart of humanity.
If the circulation of the blood in the body is in order, the person may be considered healthy.
If, however, there is some obstruction to the flow, either by a damaged organ or blocking of an artery, there is a serious crisis.
Similarly, in the normal course of life when routine worship, or work of the heart, is steady and the prayers rise as they should, the soul may be considered healthy.
To be sure, prayer has its own dangers of excess, when it rises too precipitously toward "devekut," when the soul aspires too intensely to Divine Union.
Rebbi Elimelech was known to take out his pocket watch in the middle of prayer in order to resume contact with time and reality, lest his soul escape.
But this is not a danger for most mortals.
–Rabbi Adin Steinsaltz
From "With All Thy Might," in In the Beginning by Rabbi Adin Steinsaltz