CHARLESTON, W.Va. -- Spring is the perfect time to give your workout regimen a little wiggle room. It's all about renewing the mind, body and spirit. If you're someone who replicates the way you exercise day after day, chances are your systems are bored and progress is at a standstill.In fact, your muscles, heart and lungs are unchallenged by the same old routines, songs, patterns, pace, timing, scenery and probably that worn out T-shirt too. Adding variety in all of the above is the best strategy toward meeting your goals, feeling more energetic and unlocking the fun in fitness.Human hamster wheelIs this you? From the Urban Dictionary: The human mounts the device and peddles, strides, rows or pumps their way to nowhere like a hamster on a wheel. We've all either done it or seen it. StairMasters, bikes and rowing machines are some of the machines you can jump on for a mindless cardio workout. However, spending an hour in moderate, steady-state, repetitive movement won't ever give you that strong, lean, durable body you long for.Spring freeTo make big strides in your fitness level and improve how you look and feel, change the way you move. One way is to simply rev up your steady-state cardio into a high-intensity interval training (HIIT) workout. This is a training technique that alternates between short periods of high-intensity activity and longer periods of low-intensity or recovery activity. HIIT can quickly enhance your performance, stamina, lung power and calorie burn.Quick-slow walking planHere is an HIIT walking example that can be used with other types of cardio exercise, such as running, rowing, cycling, swimming or anything that can be speeded up and slowed down. Keep in mind that on a scale of zero to 10, moderate cardio intensity (which can be sustained for a long time) is at 5 to 6. High intensity is at 7 or above, and recovery intensity is back down at 5 to 6.Following the accompanying chart, begin with a light to moderate five-minute warm-up and end with a five-minute cool-down. Alternate one minute of speed work (walking very fast, jogging, walking a hill or incline) with two minutes of recovery work (recovering at a slower pace, no incline, less challenging).Efficient workNotice the entire HIIT time is 25 minutes compared to a 60-minute treadmill experience, which allows you to fit in a workout morning, noon or evening. The HIIT also will yield far more in terms of overall performance, potential for fat burning, speed and cardio-respiratory function.Not for everyoneWhether you like to train like a tortoise or the hare, both types of training still offer health benefits. People with heart disease, high blood pressure, arthritis or who are older than 60 should consult their health-care provider before starting an HIIT program. Those who are given the green light but want a forgiving surface should consider taking this workout to a pool, which will remove impact of running, walking, swimming, kicking in the comfort of the water. Also, avoid this type of training on consecutive days and start with one HIIT workout a week and gradually add as your body adapts.If you are ready and committed to renew your workouts, think about adapting your cardio work into an HIIT format and watch it move your fitness level to a new personal best.Cindy Boggs, wellness presenter and author, is an ACE-certified instructor/trainer. Send your questions about fitness, training or health to firstname.lastname@example.org. Look for her award-winning fitness advice book, "CindySays ... You Can Find Health in Your Hectic World" on her website, www.cindysays.com.