1. Act your age. Improper technique and working out too aggressively are the most common causes of workout injury, according to Joseph Marotta, MD, an orthopedic surgeon in Troy, N.Y. The result? Strained and inflamed muscles. “Don’t wing it at the gym,” he says. “People think they can start off as they were 25, although they haven’t seen a weight in 30 years.”

2. Get a check-up. Have a general physical to make sure your heart and lungs are ready. If you have hypertension or heart disease or if it runs in your family, even if you haven’t had any cardio problems – have a stress test and get your doctor’s okay. For people with arthritis, Dr. Marotta says, “See a physical therapist to ensure you’re not overtaxing yourself.”

3. Wear good shoes. Good athletic shoes, says Dr. Marotta, can maximize arch support and shock absorption. And your summer walking or jogging shoes will get stiffer and harder in cold weather. Counteract this with over-the-counter gel inserts and foam insoles, or custom orthotics molded to the foot.

4. Tune into your body. Be sensitive to changes in your range of motion. Marjorie Albohm, president of the National Athletic Trainers Association, advises to take note of a change in stride or in the way you swing your leg or turn. She says, “If you’re not performing as you should, your body is warning you to stop what you’re doing.”

5. Maintain a healthy heart rate. A maximum healthy heart rate is your age subtracted from 220. Marotta says, “You should stay between 40 to 60 percent of your maximum for a sustained, steady workout.” If your heart is racing way above that, you’re working yourself too hard.

6. Mix it up. Perform exercises that fulfill the body’s need for balance, flexibility, strength and cardiovascular health. Vonda Wright, MD, an orthopedic surgeon and author of Fitness After 40: How to Stay Strong at Any Age (Amacom, 2009), says, “If you’re only a walker, add variety by walking in a pool or doing elliptical training. And do resistance training to unload the knees. Change the way your joints experience the pressure.”

7. Ice it. Put ice on a newly sore joint or muscle right after exercise to minimize inflammation.

8. Ease into it. Even if you’ve been exercising for years, you need to take it slow when starting a new regimen. For instance, if you’ve been logging miles on a treadmill and suddenly take to the streets, the reduced shock absorption will impact your legs and lead to joint inflammation if you don’t work up to it gradually.

Similarly, if you’re going to start using weight machines, start with stretching and low-resistance activities that improve the flexibility of your tendons, muscles and joints. Then, add resistance and repetitions over time. Your body will get stronger over time.

Dr. Marotta says, “Don’t increase speed, distance, intensity or incline more than four to 10 percent a week.”

9. Dress appropriately for the environment. In warmer weather, wear comfortable, lightweight clothing that promotes evaporation and wicks sweat away from the body. In colder weather, wear layers that you can take off as your body heats up.