treadmill.There are a different types of workouts.You can warm up then go all out for a mile or 2 then cool down.Or what your supposed to do if you have the time is to warm up and try to jog 3 or 4 miles at a steady rate.This should burn more fat and make you sweat much more.Try to switch up the cardio to.Somepeople cant run for long periods of time because it hurts their joints ect.If that then try the eliptical