After retiring from the Army, Glen returned to Houston. He felt that there would be more opportunities to grow his practice in a city such as Houston, rather than in Central Texas, the location of his last duty station.
Glen founded New Horizons Counseling Services. He later worked for the Texas Department of Corrections at the Jester Unit in Sugar Land.
Glen earned his Ph.D. in 1999 at the age of 62.
At the time of his death, Glen worked as a forensic psychologist.