How does one discern a calling to the vocation of religious life? Approaching this from a Catholic perspective, I'd like to ask believers how they came to know that they were called to join the religious life (as a brother or nun), as opposed to the other vocations (priesthood, marriage, single life etc). Rephrasing the same question, what should a believer look for when discerning whether they are called to the vocation of religious life?
Here are some resources:


Vocation to the Religious State by St. Alphonsus de Liguori
Vocations Explained: Matrimony, Virginity, the Religious State and the Priesthood by A Vincentian Father.
Vocations by Rev. William Doyle, S.J.
Religious Vocation: An Unnecessary Mystery by Fr. Richard Butler, O.P.


See also Pope Pius XII's apostolic constitution Sede Sapientiæ on vocations to the religious life says (part II.) that two necessary conditions must be met when discerning a vocation: that one is called by God and called by the Church.