Then I suggest making this very simple change to your cardio routine. Incline training is the way to go. If you are using a treadmill, change your incline gradually so you can get used to the different challenge. Your goal is to get to the higher incline ranges on your machine.
If you are a runner or walker, choose different terrains for your cardio. Ditch the smooth community path and head for the hills!
Incline training burns a ton of calories, trains your legs harder and allows you to move more slowly while still ramping up your fitness level and dropping weight. Moving more slowly also is much easier on the joints.
Someone weighing about 160 lbs, walking at an energetic 5.6 kph (3.5 mph) on a flat treadmill or terrain would burn approximately 314 calories per hour. However, if the same person added a fair amount of incline, s/he would burn about 657 calories. (woman.thenest.com).
So aim higher in your cardio training!