Most of us wish we were thinner or are actively dieting. If you have pounds you want to lose, fall is a great time to start an exercise and weight loss program. Getting in the habit now will help you stay on track during the holidays. This simple 12-week plan was developed by Bob Greene, Oprah Winfrey's trainer, to help you change your diet and ease into exercise gradually. The secret to this plan is that it requires you to steadily make small yet effective diet and lifestyle changes that lead to a permanently healthier, thinner you.

Weeks 1 and 2: Avoid fat-burning pills and fad diets—the prescription for permanent weight loss is eating less and getting more exercise.

• Diet change: Replace soda with water, unsweetened tea, or fat-free milk. Limit diet soda.
• Exercise: Do 15 minutes of moderate cardio activity, five times per week.

Weeks 3 and 4: Cutting calories to lose weight works, but real results require exercise.

• Diet change: Substitute 100% whole grain bread for white bread. Incorporate whole grain pastas and brown rice into your diet.
• Exercise: Increase your activity to 20 minutes per session.

Weeks 5 and 6: To identify the emotional reasons behind overeating, keep a journal to determine when you tend to overeat and what the triggers are.

• Diet change: Cut out trans fat (check labels).
• Exercise: Increase your activity to 25 minutes per session. Add strength training three times per week. Do one or two sets of 8 to 10 reps for each move—triceps extension, biceps curl, squat, stomach crunch, torso rotation, lat pull, incline press, and standing butterfly.

Weeks 7 and 8: Your initial enthusiasm for dieting might be waning. Consider ways to stay motivated.

• Diet change: Eliminate fried foods—try foods that are roasted, sautéed, or baked.
• Exercise: Increase your activity to 30 minutes per session. Continue with the strength training.

Weeks 9 and 10: Revisit your initial goal. If it's not realistic, rethink what you want to achieve.

• Diet change: Switch from whole or 2-percent milk to 1 percent or fat free. Try fat-free yogurt. Try soy milk.
• Exercise: Increase your activity to 35 minutes per session. Add another set of 8 to 10 reps to each strength move.

Weeks 11 and 12: You've lost weight, but are you skipping workouts or allowing second helpings? It's not a race—the longer you stay with it, the easier it gets.

• Diet change: Try limiting alcohol to cut calories. Substitute sparkling water with a splash of fruit juice.
• Exercise: Increase your activity to 40 minutes per session. Continue with the strength training.