The workout: Walking Calories burned: 181 for 45 minutes (140-pound woman at 3.5 MPH on a level surface)Trainer tips: Walking engages almost every muscle in the body, says celebrity trainer Holly Perkins. If you’re an exercise newbie, start with an easy 10-minute walk in your hood and add 10% more time each week. Ready to upgrade your leisurely stroll to a calorie scorcher? Try speed changes—alternating slow and fast walking—or hike a hill. If you are walking on a curb, go up and down the step as you go for added resistance. More from Prevention: 14 Fun Walking Workouts The workout: In-Line Skating Calories burned: 572 for 45 minutesTrainer tips: Wear protective gear and start in an area that has a flat surface, like a parking lot, says Perkins. (Sidewalks tend to have cracks and bumps.) Take short strides and crouch down to keep your center of gravity close to the ground. Once you get comfortable, do an uphill repeat circuit: Go up and go down a hill carefully and repeat five times. “It’s a great calorie burn,” says Perkins. “It also boosts your metabolism for several hours after the workout.” The workout: Zumba Calories burned: at least 350 for 45 minutesTrainer tips: Tell the instructor it’s your very first time taking this Latin-inspired cardio dance class so she can pay special attention to your form. This vigorous dance workout provides ample distractions—fun music, lots of arm waving—so you may not notice how hard you’re actually working. Dancing is a good pick for people who already have a regular workout routine, says Pire. “A Zumba class will keep them on the exercise wagon,” he says. “Working out with a group is fun, and for some people, having friends with them in a class will make them stick with a workout.” More from Prevention: The 5 Best Pain-Fighting Workouts The exercise: Step Climbing Calories burned: 429 for 45 minutesTrainer tips: Whether it’s bleacher steps outdoors or a VersaClimber or StairMaster at the gym, moving on up means your weight will go down. Since you have to hoist yourself skyward, climbing automatically falls into the “moderate to vigorous” range where you burn more calories—and boost your heart health. But if you find yourself starting to tire, step away from the staircase or hop off the machine. “As you fatigue, your balance becomes challenged, so you might fall off,” says Pire. The exercise: Cycling Calories burned: 381 at a moderate pace for 45 minutesTrainer tips: Take your workout outside! But get fitted for a bike to ensure the most comfortable ride and to avoid knee problems, says Perkins. Love group exercise? Sign up for a spin class for heart-thumping music and a little healthy competition. Perkins recommends investing in padded bike shorts to prevent next-day seat soreness and inexpensive clip-in shoes to get the most out of your workout. These specially designed shoes position your foot in the correct angle to exercise muscles more efficiently. To boost your burn, alternate sprints with moderate speeds, says Pire. The exercise: Elliptical Trainer Calories burned: 333 at a moderate pace for 45 minutesTrainer tips: “This is a no-impact workout,” says Pire. “Ellipticals are easy to use, pain-free, and an easy way to start exercising for most people.” He recommends hopping on a machine with an upper body component so you can engage even more muscles—and blast more fat. Can’t find a machine that lets you pump your arms? Let go: Some research suggests that leaning on machine armrests during exercise reduces calorie burning. More from Prevention: 6 Must-Have Home Workout Tools The exercise: Swimming Calories burned: 333 doing freestyle at a slow to moderate pace for 45 minutesTrainer tips: Even if you are overweight, have joint issues, or suffer from arthritis, you can still make a splash—and sneak in a weight-bearing exercise workout, too. You naturally lose muscle mass as you age. And less muscle means you burn fewer calories, causing the dreaded weight creep. Start at just 30 minutes, taking in slow laps, says Pire. Then make a game out of it: crawl in one direction, breaststroke back; or backstroke one way. The exercise: Rowing Machine Calories burned: 333 for 45 minutesTrainer tips: The most under-used piece of gym equipment is actually a full-body toner, says Pire. It’s also one of the few cardio machines that engage your upper body muscles. Rowing helps with posture, since it makes your upper back stronger and you stand up straighter, says Perkins. For proper form, push with your legs and pull with your arms. The harder you pull, the more resistance and arm sculpting you get. And the faster you go, the more calories you blast! More from Prevention: Find Your Perfect Calorie-Burning Dance Workout