A lot of people prefer the elliptical and treadmill for cardio to reduce impact on their knees. If you're one of those people, try this...
Do your cardio on these machines without holding on to the handles at a speed that you can control safely. Doing so will also engage some core stabilizers, meaning you're teaching your body how to stabilize itself versus relying on you to hold on to something. As your stability and balance improve, your comfort level and speed will follow.