Treadmills and stationary bikes aren't the most thrilling pieces of gym equipment. Rocky Balboa knew this. That's why he preferred dragging a sled through a frozen field to get his cardio.
But you don't need to live in a cabin in Siberia to get a real workout. Try these tips from Cameron McGarr, head of personal training at Equinox in Woodland Hills, CA, for a cardio routine that'll kick your ass.
1. Try a weighted step mill
Strap on a weight vest or grab a pair of dumbbells. Come to a step mill (or a set of real stairs) and get climbing. Keep the speed at a manageable pace. The weights provide plenty of intensity.
2. Do an unpowered treadmill run
Set a treadmill to a low incline, then shut the power off. Move the belt with your own power by "pawing" at it with your feet. You'll have to maintain a high intensity to keep the belt moving.
3. Perform a military run
Hold a light barbell (or one of the Body Bars found in most aerobics studios) overhead, keeping your elbows locked out while you run on the treadmill. Give yourself some space (aka don't do this with people on either treadmill beside you).
4. Complete kettlebell intervals
Alternate between 10 heavy kettlebell swings and running 400 meters. Go for as long as you can.
5. Crank out bear crawl intervals
Place your feet behind the treadmill and put your hands on the belt. Crawl with your hands for 60 seconds, then run (yes, with your feet) for 60 seconds.