Here are a few key words of advice from some leading fitness professionals:

Q. What do you think is the most important thing that makes or breaks a fitness program?

Gilad Janklowicz, fitness instructor and host of "Total Body Sculpt" on FitTV (www.bodiesinmotionwithgilad.com): The most important elements in a fitness program are:

1. Sustainability: Each person should find his favorite fitness activities and then work them into his weekly schedule at a time of day that will be easy to commit to.

2. Setting realistic goals: A step-by-step approach is very important for beginners as well as for advanced exercisers. Don't set contracts in your mind that your body is not ready to meet.

3. Consistency: It's better to do a little bit every day than to push hard for a short time and then give up.

Q. What is the one food or meal you always eat before training?

Jillian Michaels, trainer on The Biggest Loser and author of "Master Your Metabolism" (www.jillianmichaels.com): I eat one hour before training, and I always make sure there is a combo of protein and low-GI carbs. For example, 1/2 cup of low-fat cottage cheese on a piece of Ezekiel toast. Or scrambled egg whites and sliced tomatoes.

Q. What specific foods promote muscle development?

Paul Goldberg, certified strength-and-conditioning specialist who works with Olympic and professional athletes: First you need to fuel your workout, so clean-burning complex carbs are a must: whole-grain breads, whole-wheat pastas and pancakes, 100 percent real fruit juice. Then you need to have clean protein to rebuild your muscles: salmon, tuna, chicken, low-fat milk, cheese, beef, legumes, nuts and beans. Timing is crucial as well. You need nutrients on board and in your system at the right times to promote optimal growth and recovery.

Q. What are the biggest strength-training mistakes women make?

Eric Cressey, CSCS, author of "Maximum Strength" and fitness blogger (www.EricCressey.com): A few that come to mind:

1. Not using enough resistance;

2. Using machines;

3. Substituting yoga and/or Pilates for strength training; they provide different training effects altogether and should be treated accordingly;

4. Poor footwear (particularly wearing shoes with too much heel-lift — both in and out of the gym);

5. Planning their strength training around their cardiovascular exercise and not vice versa;

6. Not using multi-joint movements.

Charles Stuart Platkin is a nutrition and public-health advocate, and author of "Breaking the FAT Pattern" (Plume, 2006). Sign up for the free Diet Detective newsletter at www.dietdetective.com.