Let’s debunk a couple of big metabolism myths right away:

Myth: Aging slows your metabolism.

Reality: The tendency to put on weight does increase with age, and as we get older, metabolism can slow. But adding another candle to your birthday cake isn’t to blame. Nope, if your metabolism is slowing down, you can chalk it up to less-than-ideal health habits (like eating that extra slice of cake or skipping workouts).

So what can you do to prevent the decline of your metabolism through the years? For starters, check your lifestyle choices, such as your sleep habits. Researchers have found that getting less than 7.5 hours of sleep slows metabolism. Adequate sleep keeps the body in good working order, and 8 hours or more of rest is better still.

Keep (or, ahem, start) exercising. It’s an obvious way to encourage the body to burn calories. A bonus: The lean muscle you add to your physique will burn calories faster than your stored fat will. And the exercise itself creates an afterburn of sorts that gobbles up even more calories. Be sure to change up your routine every couple of months, too. Otherwise, as your body adapts to your usual workout, a routine becomes a rut. The result? Fewer calories burned.

Finally, mind what’s on your plate. Eating too little will slow your metabolism by convincing your body it’s at risk for starvation, prompting it to burn fuel much … more … slowly. In the other extreme, overeating will force your body to store the excess fuel as bulky, low-calorie-burning fat.

Myth: Your metabolism is genetically programmed and can’t be changed.

Reality: As with many genetic traits, your body may have a preference for a certain behavior. There is some wiggle room in the matter, however. Just how much is determined by the choices you make for your body.

By taking care of your metabolism—proper exercise, healthy diet, good lifestyle habits—you can train your body to deliver its best possible performance. Lack of exercise, poor diet, and general lack of attention to your health, on the other hand, can thwart even the best natural metabolism.