Start out easy on yourself to lower risk of hurting joints or tendons.
Mon/Wed/Fri cardio: Go for a brisk 45-minute walk, preferably including up and down terrain.
Tues/Thurs/Sat muscular: Spend 30 minutes climbing up and down the local bleacher stairs (or a nice steep hill). Take regular short rests.
Step it up a little.
Mon/Wed/Fri cardio: Add short stints of jogging to your walk.
Tues/Thurs/Sat muscular: same 30-minute routine, just cut down on rest time
Start getting focused.
Mon/Wed/Fri cardio: Begin pushing yourself, walking less and jogging more.
Tues/Thurs/Sat muscular: Same 30-minute routine, add three squats and three lunges (don't use weights) alternately during short rest periods.