I have known many Glenmary priests and sisters, and worked with them for years on a cooperative project with our former parish and Glenmary Applachian missions. This experience has been uniformly positive and the ones we know are without exception good and holy priests and religious, faithful in teaching and practice.
I second above poster, join as a mission associate or through a parish venture (used to be called Connective Ministries, I think it is now called Taste and See, where parishioners can spend a week in a rural parish working and serving). there is also a summer camp experience for prospective seminarians and lay missioners.