If you are barely breaking a sweat anymore and feel like you are simply going through the motions with your routine -- kick it up a notch! Playing with the inclines and speed will take your mind off of counting down the minutes that pass. It will also make the workout more of a challenge, meaning more calories burned even faster!
Pretty much any activity that gets your blood pumping is cardiovascular. When your heart rate rises, muscle cells break down sugar and fat for fuel, burning calories. Clearly there are a ton of ways to do this, but exercise physiologists lump cardio into three buckets -- long, slow distance (LSD), medium hard (tempo) and high-intensity interval training (HIIT).