Regulations approved by the Director shall govern the earning of good conduct allowance. The regulations shall require, as a condition for earning the allowance, that a prisoner participate in an appropriate educational, training, work, counseling or substance abuse program or other program intended for his rehabilitation, as provided in § 53.1-32.1. The amount of good conduct allowance to be credited to those persons eligible therefor shall be based upon compliance with written prison rules or regulations; a demonstration of responsibility in the performance of assignments; and a demonstration of a desire for self-improvement.