When it's time to hit the gym, most of us are in a serious time crunch. If your idea of a gym workout involves walking on the treadmill, riding the stationary bike or just doing laps around the track, you could be wasting your time. Sweating up a storm with basic cardio feels good in the moment, but you won't be doing your muscles any favors with that routine.

The best way to maximize your time is to do resistance training; you can burn up to four times as many calories by adding weights to your routine in the form of power squats, lunges and other weight-bearing sequences. Here are a few ideas to ramp up your usual cardio routine and blast off extra calories in no time:

1. Wear ankle weights. If you insist on strapping on those running shoes and doing laps around the track, bump up the resistance by wearing some ankle weights. These will make your usual jog that much more challenging and will give your lower legs a serious workout.

2. Play with resistance bands. Resistance bands use your own weight for resistance and help you strengthen and tone up muscles in a flash. You can do simple lunges, squats and pull ups with a set of bands by your side; they're perfect for that midday training session at the office or anytime you need to squeeze some training into your day.

3. Wear weighted hand gloves. Can't get away from the treadmill or elliptical machine? Pull on a pair of weighted hand gloves that add some resistance to your lower arms and help you tone up.

4. Do your crunches with a medicine ball. A 5 lb. medicine ball is all you need to add some power to your crunches. Just hold the ball with both hands above your head as you perform your oblique twists and ab crunches on the yoga mat. You'll feel the burn much faster and may finally see some results from your hard work.

5. Jump into the pool. Those ladies in the water aerobics class know a thing or two about resistance training. Performing simple walking or stretching routines in the water is a great way to burn calories and get those muscles in great shape.