To feel energetic you need to eat healthfully, exercise regularly and get enough sleep. But what if you've done all those things, and you're still not performing at your peak? Your emotions may be to blame. According to a survey of endocrinologists, nutritionists and specialists in sports medicine conducted at The Chestnut Hill Institute, a center for research and psychotherapy in Boston, at least 70 percent of our perceived energy is attributable to our emotional state.

Here's an example of how emotions affect energy: You're running a race. It's the last mile. You're physically exhausted. Then, seemingly out of nowhere, your hope, desire and the sheer joy of accomplishment give you an extra boost; you pick up the pace and sail to the finish.

You've been rescued by emotional energy more often than you realize -- every time you're tired or sick but your optimism keeps you going. You've also been dragged down by emotional fatigue -- you're perfectly healthy, but worry, envy, discouragement or stress eat away at your inner resources, leaving you feeling drained. Fortunately, you have the option of managing your emotional energy. You simply need to take measures to boost it, just as you do for your physical stamina. Here's how.

Keep it new. High-energy people are always trying things they've never attempted before, even when the old and familiar patterns seem good enough. They never let themselves get stale.

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- Every week, add something new to your life. Try a food you've never eaten; take an alternate route to work, the store or the gym; listen to a recently released CD; read a new genre of book.

- Do something you do all the time in a different way. Are you a yoga devotee? Take a class with a new teacher, try a different kind of yoga or get a book or video with poses you haven't done before.

- Once every month or two, get radical. Take up a new sport; change your hair color or cut; get away for a long weekend to a new place.

Be your own boss. Living up to other people's expectations and demands is exhausting. Of course, helping others can boost your emotional energy, but only when it's your choice to pitch in.

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- Examine your career, relationships and responsibilities, and ask yourself if you're mainly doing what someone else wants or what you want. If you aren't setting your own goals and fulfilling your own desires, it may be time for a change. - Venture out solo. Go to a movie or a restaurant by yourself, so you can choose exactly what you want -- or treat yourself to a minivacation where you set the genda.

Conquer a fear. Facing a fear is scary, but it's also a great opportunity to eliminate a source of stress from your life and get an energizing high at the same time.

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- Do something on a small scale that frightens you, just enough for you to say when you've done it, "Well, that wasn't so bad." Afraid of heights? Take a hike in a hilly rea where you'll gradually walk to higher ground. Scared to speak in public? Start by making toasts at dinner parties with friends.

- Talk about your fear with someone understanding -- or if it's a common phobia, join a support group or take a class to help you overcome it.

Enjoy yourself. Fun is fuel. That's why athletes, performers or anyone who genuinely enjoys what they do for a living so often excels at it. You can't have a blast every second, but being more playful or taking things less seriously will help keep you going.

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- Dismiss the idea that there's always a right way to do things. Perfectionism can turn everything into a struggle, so simply aim to do your best.

- Smile. There's abundant research suggesting that feelings follow actions. Once you start smiling, you just might boost your mood, and then you'll start having fun.

- Think up a list of things you've enjoyed in the past. If it was fun once, it will be again. Then go do it.