Fitness training is a science, and like all branches of science it relies on method. Fitness-training expert Stacie Sanders gives her best tips for working out to stay healthy and fit:

• Train daily, but incorporate rest periods for individual muscle groups. For consistency and greatest effectiveness, it’s best to undertake some form of exercise every day, but don’t expect to work every part of the body every day. Alternate between muscle groups so each has a chance to rest and build up before being stressed again. One program with proven results: Do weight training on Mondays, Wednesdays and Fridays; do cardiovascular workouts on the other days.
• Train in consistent intervals. Avoid long or varied periods between workouts. If you can’t work out every day, try for every other day — but not, for example, three days in a row and then a week off.
• Consult a physician, even if you’re young and healthy. No matter who you are, it’s a good idea to get a general health assessment from a physician before undertaking a rigorous exercise regimen.
• Go slow. Exercising faster or at a frenzied pace won’t get you fit any sooner. In any particular exercise, you should be striving to isolate the muscle or muscle-group you’re working on. Reps should be methodical, uniform and deliberate. Focus, technique and control are important. Speed is not.
• Keep weights balanced. Work each arm (or leg) the same amount as the other. Don’t vary weight on one side because you’re right-handed or left-handed. Strength will build uniformly by consistency.
• Exercise the larger muscles first. Muscle-building and toning will be more effective if you tire the larger muscle in a region (e.g., the triceps) first, and then move on to the smaller (e.g., biceps).