Inclusion Criteria:

1. Be seeking treatment for their MA dependence;

2. Be 18 years of age or older, and 45 or younger for males, 55 or younger for females;

3. Meet DSM-IV-TR criteria for MA dependence;

4. Have vital signs that are within clinically acceptable normal range, e.g., resting
pulse between 50 and 90 /min, blood pressures between 85-150mm Hg systolic and
45-90mm Hg diastolic;

5. Have a medical history and physical examination that, in the judgment of the study
physician or Principal Investigator, show no clinically significant contraindications
for study participation;

6. For females, provide negative pregnancy urine tests before randomization (and for the
sub-sample, another negative test before the final PET scan at the conclusion of the
intervention).

Exclusion Criteria:

1. Clinically significant heart disease or hypertension; unstable pulmonary or
cardiovascular disease that would interfere with participation in exercise regimen

2. Neurological or psychiatric disorders as assessed by MINI or clinical interview, such
as psychosis, bipolar illness, Tourette's syndrome, major depression, organic brain
disease, dementia, or any other neuro-psychiatric disorder that would require ongoing
treatment or that would make study compliance difficult;

3. Musculoskeletal disease that would prevent participation in exercise regimen

4. Baseline ECG showing evidence of cardiac ischemia, arrhythmia, or other clinically
significant abnormalities

5. Untreated or unstable medical illness including: neuroendocrine, autoimmune, renal,
hepatic, or active infectious disease (other than HIV) that requires immediate
medical attention;

6. Clinically significant abnormalities in hematology and chemistry laboratory tests
that may make participation hazardous;

7. Have HIV and unable to obtain a clearance for participation from his/her AIDS medical
care provider;

8. Pregnant;

9. Any other illness, condition, or use of medications that, in the opinion of the PI
and/or the study physician, would preclude safe participation or completion of the
study.