St. Francis de Sales when asked how much one should pray said that you should pray for half hour a day, unless you are really busy. If you are really busy, you should pray for an hour.
The great doctor of the Church understood that in being busy we are concerning ourselves with earthly things. Like Martha, the industrious sister of Lazarus and Mary, fluttering around concerned with the tasks of hospitality, but missing the presence of the bridegroom. We must, like Mary, choose the better half and subjugate our earthly concerns to the transcendent.