Actually, that is a very simple question.
It takes a special charism from God.
New orders arise from within the Church at all times, but most of the well-known orders have come along at times of difficulty for the Church.
For example, the Franciscans and Dominicans began in the 1200's during a time of widespread corruption in the Church. Many of the laity were being alienated because of this. The Dominicans- "teachers and preachers"- were founded by St. Dominic and the Franciscans- "poor little brothers"- were founded by St. Francis of Assisi. The Dominicans obviously taught and preached the Faith. The Franciscans ministered to the poor and offered a powerful message of peace and reconciliation.
In the 1500's, the Jesuits were founded by St. Ignatius of Loyola. During this time of Martin Luther and the birth of Protestantism, the Jesuits were of critical importance to the Church. They defended and propagated the faith. The work of the Jesuits stopped the rapid spread of Protestantism. Several Jesuits were martyrs in America.
These are only a few examples.
Without that "special charism" I mentioned earlier, these guys wouldn't have had thousands of people decide to join them, including many who died for doing so.