I notice that AM cardio after an overnite fast produces the most fatburning results. Just don't go overboard on it. 20-25minutes daily is quite a good number. Anything more and I feel things become to catabolic and muscle wasting. Getting your veins and whatnot though and burning fat is more about diet than about cardio. Thats not too say cardio isn't important, just make sure all you duckies are in line.