So … you've decided to be more active. The first week of your plan goes great: You get out your running shoes (and actually use them for running), and you’re feeling stronger, energized and more alert. You're off to a great start!

Then comes the second week: You're getting bored, and by the end of the week, you've slipped back to your old ways. Sound familiar?

Here’s how to actually make it to the third week and beyond:

Set Realistic Goals
Saying to yourself you want to have the body of a supermodel is a recipe for disaster. Only 2 percent of all women have a tall and slender model’s build. The other 98 percent of us are petite or curvy or round -- and equally beautiful! Instead of trying to achieve the impossible, set milestones: “I want to be able to run for 30 minutes without stopping.”

Work out Early
Studies show that people who exercise first thing in the morning are more likely to stick to their routine. Why? Well, no sudden movie invitations or yearbook meetings pop up at 7:30 a.m. Wake up half an hour early to squeeze in some yoga stretches before school.

Have a Workout Partner
Exercising with a friend is a great way to keep you on track. You and a BFF could meet up at the skating rink every Thursday evening or walk home from school together rather than taking the bus. Be each other’s personal cheerleader!

Spice up Your Routine
Following the same run day after day … after …day … can get boring. So shake things up with other forms of activity, like biking through your neighborhood or even dancing to your favorite songs around the bedroom.

Move It Indoors
As it gets chillier outside, it’s easy to just curl up on the couch. One way to combat the cold-weather workout blues is to exercise at home. Consider investing in a set of exercise DVDs or playing Wii fitness games to perfect your virtual ski jump or hula-hooping form.

Be an Active TV Viewer
While you watch your favorite sitcoms, march in place, do lunges, perform tricep dips off the couch or lift light hand weights. During commercials, do push-ups or sit-ups. In the course of a full one-hour show, you probably have about 20 minutes worth of commercial interruption to get the job done.