It depends on how bad or good your cardio already is. If you are just starting out and have bad cardio, do 1 mile daily for 3 days. Rest on day 4. On days 5-7, do 2 miles. The next week on on days 1-3, do 2 miles. Day 4 rest. On days 5-7, do 2 miles again. Just repeat that process and slowly build yourself up to at least doing 5 miles daily with at least one rest day per week, depending on how you feel. Let me know how it goes for you man.