When you change your thinking from "I can't work out" to "I will burn 100 calories just like that!" stopping holiday weight gain is simple with these tips from Fitness magazine.

For time-crunched days, try these mini-workouts. Each burns 100 calories, and most take less than 15 minutes-and if you do just four exercise hits a day, you can whittle away more than three pounds of fat a month.

RUNNING UPSTAIRS

Time to burn 100 calories: 7 minutes

Scamper up the stairs of your house, turn your stairwell at work into a gym, or find a steep hill to tackle on your regular running route. Count only the time that you spend going up-for knee safety, always walk downstairs instead of running.

JUMPING ROPE

Time to burn 100 calories: 10 minutes

Try jumping twice per second (i.e., if you count out "one thousand one," that should equal two jumps). If you're more adept at fancy footwork, mix it up: Hop on just one foot instead of two, twist from side to side, or travel around the room as you're jumping.

RUNNING

Time to burn 100 calories: however long it takes you to run one mile

If you run a 10-minute mile, you'll incinerate about 100 calories in 10 minutes; running a 9-minute mile brings it down to 9 minutes, and so on. The easiest way to inject more speed into your stride: Pump your arms as you run.

CALISTHENICS

Time to burn 100 calories: 15 minutes

You'll remember these from your high-school gym-class days: Push-ups, sit-ups, jumping jacks and squat thrusts are not only standards, they're great strengtheners and calorie burners, too. Do a combination for one great workout, or incorporate them into a circuit program.

RACEWALKING

Time to burn 100 calories: about 15 minutes for a 12- to 15-minute mile

Walking sometimes gets a bad calorie-burning rap, but that's because most people don't walk quickly enough to see good results (leisurely strolls don't cut it). Speed it up for a great calorie blast: Pump your arms back and forth and focus on pushing off with the toes of your rear foot to pick up your pace.

Note: All calorie counts are for a 130-pound woman.

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