It’s got to be high intensity, whatever the workout is, if you’re going to torch calories — not just burn them,” says Bret Emery, a behavioral psychologist and weight loss specialist based in Weston, Fla. “Heart rate is key. That’s the speedometer of the body. If we speed the body up, it will burn more calories, just as a car will burn more fuel if it speeds up. The following workouts will zap calories, but they’ll also push your body way past your comfort zone. So check with your doctor before taking on the challenge. Don’t just tell your doctor you want to work out, let him or her know exactly what you’re planning to do. That way, your doctor can make sure you’re ready.

1. Chase Squires is the first to admit that he’s no fitness expert. But he is a guy who used to weigh 205 pounds, more than was healthy for his 5’4″ frame. “In my vacation pictures in 2002, I looked like the Stay Puft Marshmallow Man at the beach,” says the 42-year-old Colorado resident. Squires decided enough was enough, cut out fatty food, and started walking on a treadmill. The pounds came off and soon he was running marathons — not fast, but in the race. He ran his first 50-mile race in October 2003 and completed his first 100-miler a year later. Since then, he’s completed several 100-mile, 50-mile, and 50k races.

His secret? “I’m not fast, but I’m consistent,” says Squires, who says consistency is his best tip for maintaining a successful fitness regimen.

2. Set Realistic Goals – “Don’t strive for perfection or an improbable goal that can’t be met,” says Kara Thompson, spokesperson for the International Health Racquet and Sports-club Association (IHRSA). “Focus instead on increasing healthy behaviors.”

In other words, don’t worry if you can’t run a 5K just yet. Make it a habit to walk 15 minutes a day, and add time, distance, and intensity from there.

3. Use the Buddy System -Find a friend or relative whom you like and trust who also wants to establish a healthier lifestyle, suggests Thompson. “Encourage one another. Exercise together. Use this as an opportunity to enjoy one another’s company and to strengthen the relationship.”

4. Make Your Plan Fit Your Life – Too busy to get to the gym? Tennis star Martina Navratilova, health and fitness ambassador for the AARP, knows a thing or two about being busy and staying fit.

Make your plan fit your life, she advises in an article on the Midwest Training Center web site. “You don’t need fancy exercise gear and gyms to get fit.”

If you’ve got floor space, try simple floor exercises to target areas such as the hips and buttocks, legs and thighs, and chest and arms (like push-ups, squats, and lunges). Aim for 10-12 repetitions of each exercise, adding more reps and intensity as you build strength.

5. Be Happy – Be sure to pick an activity you actually enjoy doing, suggests Los Angeles celebrity trainer Sebastien Lagree.

“If you hate weights, don’t go to the gym. You can lose weight and get in shape with any type of training or activity,” he says.

And choose something that is convenient. Rock climbing may be a great workout, but if you live in a city, it’s not something you’ll be doing every day.