Taken from the Powerbar site.

It’s Not “Wimping Out” When Your Body Needs the Rest

I’ve been following a training program for several months, but there are days when I just don’t feel like doing my workout. I don’t know if my body’s trying to tell me something or if I’m just wimping out.

- Jason W., Portsmouth, ME

I'm certainly a fan of getting out there and trying to get a workout started, especially since you can often get through a whole workout as long as you can get through the first 10-15 minutes. However, “wimping out” is sometimes the smartest thing you can do. There are times when I wish the athletes I work with would listen more closely to their bodies and call it a day when they're not responding to their workouts. Here are a few good ways to tell if turning around is the right thing to do:

1. Your heart rate/power output doesn’t match your perceived exertion. Though perceived exertion is often dismissed as being “unscientific”, I believe it has to be taken into consideration when talking about training. You know how you normally feel when you’re exercising at a certain pace or intensity. If it takes a superhuman effort to raise your heart rate or power output to your normal cruising level, or to the level necessary for intervals, it’s a sign that something’s not right. Usually, it means you’re fatigued and that you’re better off doing an easier workout or taking the day off. Sometimes this scenario will even continue for a few days, but generally it won’t last more than a week. Listen to your body and give it the time it needs.
   
2. You feel like taking a nap by the side of the road or trail. Most days, you’re raring to go when you head out for a workout, but then there are days when you just can’t seem to get excited about training; you’re yawning at stop lights and daydreaming instead of focusing on your workout. On days like these, it’s important to get out there and see what happens after about 15 minutes. If you snap out of your funk and get your head in the game, then continue with the workout. If you can’t get your head into it, turn around and go home. I’d rather see you miss that one workout and come back excited the next day instead of absentmindedly going through the motions for several workouts in a row.
   

And since this is the Holiday Season, there’s one other piece of advice (it’s not completely pertinent to the original question, but it’s useful anyway): a shortened workout is better than no workout at all. So, if a holiday party or poor winter weather cuts your available time down to just 30 minutes, take it. It helps you stay in a consistent training routine and ensures that you’re not slipping backwards in your fitness progression. Shortened workouts may not move you forward as much as complete ones do, but they’ll help you keep the fitness you’ve worked so hard to build.

- Chris Carmichael