Participants were recruited to the study using various methods, including word of mouth and IRB-approved flyers posted throughout the treatment facility. Onsite study staff screened MA-dependent clients in a private study office and reviewed the informed consent protocol. After completion of informed consent procedures, participants entered a1-2week screening phase to determine eligibility, consisting of medical history, physical exam, laboratory studies, and ECG. Eligible clients were taken through study baseline assessments to inform randomization to study conditions, either an exercise intervention or health education control, using a computerized urn randomization program that stratified clients to conditions based on gender (male/female) and severity of baseline MA use (higher vs. lower severity). The cut-off point for determining lower severity MA use versus higher severity use was identified using data from previous clinical outcome studies that show the median number of days of MA use ranges from16 to 20 days at treatment entry. Hence, we defined "lower severity" as using MA for 18 or fewer days in the previous month, and "higher severity" as using for 19 or more days in the past month. The study's data management center (DMC) maintained the urn randomization program and the records that linked participant identification numbers to study condition. Study interventions were conducted onsite while participants were enrolled in usual care at the residential treatment facility; cases of early discharge from the facility resulted in premature termination from the study.