We should never forget that intensive training away from ’ordinary life’ is exactly what Jesus did in the spiritual formation of the selected few who were to be his shock troops, his ’green berets’ in world revolution. He gave them almost three years of special training away from their ordinary life.
We must flatly say that one of the greatest contemporary barriers to meaningful spiritual formation in Christlikeness is overconfidence in the spiritual efficacy of ’regular church services’, of whatever kind they may be. Though they are vital, they are not enough.

Individuals and local congregations of disciples must discover and effectively implement whatever is required to bring about the inner transformation of those who have really become apprentices of Jesus and who really do gather in immersion in the [presence of the Father, Son, and Holy Spirit] . Jesus did not give us a plan for spiritual formation that will fail, and he has the resources to see to it that it does not.

Dallas Willard (Renovation of the Heart, pp. 249-250)