Cara Kempf is a certified personal trainer with the Fitness Zone in Carmel and a group fitness instructor with NIFS in downtown Indianapolis. She can be contacted at fitnessblog@theindychannel.com.

"I am trying to lose around 10 pounds by adjusting my diet and walking. I am a little confused about the target heart rate. I am 41 years of age. After using the formula, I come up with 125. If I maintain my rate at 125, I do not feel that I am really working out at all. I usually walk between 35 to 45 minutes four to five times weekly. I do a little weight training and some yoga as well. Any advice would be helpful." -- Kelly

Thanks for writing, Kelly -- this is a very common question. First off, you have to remember that the formula is just an estimate of where your heart rate should be when you exercise. The problem with any and all formulas is that they don't take into account added factors, like what shape you might be in. I have seen 70-year-old women out pounding the pavement in the morning, and I would guess their heart rate is not the "normal" target heart rate for sedentary or semi-active women their age -- the one you would get with the formula.

Although the formula is great for giving you something to start with, I don't feel you should follow it as absolute truth, especially if you don't feel like you're exercising intensely enough. Use it simply as a guide, and then try the talk-test, or rate of perceived exertion (RPE). If you can carry on a full conversation while exercising, you probably aren't working intensely. If you can sing, you definitely aren't working intensely. You should be able to speak here and there throughout your workout, but it should be somewhat difficult to hold a complete conversation.

Then, on a scale of one to 10 -- 10 being the absolute hardest you could work out -- rate the difficulty of the exercise you are doing right then. If you want a mega-calorie-burning workout, you want to stay around seven or eight. (Although you can still burn calories at a lighter pace, it just takes longer!)

Sounds to me like you are on the right track to dropping those 10 pounds! Remember, one to two pounds per week is healthy weight-loss, and a healthy diet will be the deciding factor in the last three to five. Keep up the good work!