Smart people aren't smart just because of what they know. They're also smart because of what they believe--and what they don't believe.

And that's why smart--and successful--people never:

1. Believe their past dictates their future.

We all have limitations. We all have challenges. We all make mistakes. Don't be bound by them--learn from them.

Easier said than done? It all depends on your perspective. Take mistakes: When something goes wrong, turn it into an opportunity to learn something you didn't know--especially about yourself. (And when something goes wrong for someone else, turn it into an opportunity to be gracious, forgiving, and understanding.) Where you've been, what you've done--your past is just training. Your past should inform you, but it should never define you. Stop letting it.

2. Decide to say yes when they mean no.

Refusing a request from colleagues, customers, or even friends is really hard. But rarely does saying no go over as badly as you expect. Most people will understand, and if they don't, should you care too much about what they think?

When you say no, you feel bad for only a few moments. When you agree to something you really don't want to do, you might feel bad for a long time, or at least as long as it takes you to do what you didn't want to do--or shouldn't have to do--in the first place.

Practice saying no. In time it gets easier and ensures you can focus on doing what you really need to do--for yourself and for other people.

3. Think it's OK to interrupt.

When you interrupt someone, what you're really saying is, "I wasn't thinking about what you were saying. I was thinking about what I want to say, and what I want to say is so important you need to hear it now." Want better professional relationships? Want better personal relationships? Listen to what people say. Focus on what they say. Ask questions to make sure you understand.

Other people will love you for it--and you'll love how that makes you feel.

4. Think it's OK to run late.

I know. You're busy. You're overwhelmed. You're always running behind. And it stresses the crap out of you. (It also makes other people resent you. Whenever you're late, other people rightly assume you feel your time is more important than theirs.) Although you may think you can't help it, being late is a choice. You allow yourself to be late.

Tomorrow, start your day a little earlier. (It won't kill you.) Then arrive at your first scheduled event early. Don't worry that you'll waste time--just plan ahead and bring along whatever you need to use any "early" time to get a few simple things done.

I promise you'll feel a lot less stressed, and as a result you'll be more insightful, more creative, more decisive--simply more on in everything you do.

5. Indulge in or harbor resentment.

Take it from Nelson Mandela: Resentment is like drinking poison and then hoping it will kill your enemies. The same holds for bitterness. And jealousy. And dislike.

Let negative feelings go. When you hold onto ill will, the only person who loses is you.

6. Decide they don't have the time.

Everyone knows someone who just seems to get a lot more done than other people. It's the craziest thing. How do these folks do it? They must have no life. Actually, they have a great life. They've figured out what is important to them, and they're making it happen. Figure out what's important to you. Strip away all the stuff that isn't. Then make it happen.

We're all given the same amount of time. The only difference is how we use it.

7. Fit in just to fit in.

Though entire industries are based on holding the opposite viewpoint, no one likes you for the clothes you wear, the car you drive, or the house you live in. No one likes you for your title, either. All those are things. Other people may in fact like your things, but that doesn't mean they like you. And in all likelihood, that doesn't mean you like yourself.

Be yourself. When you stop trying to fit in or make an impression, you might lose a number of acquaintances, but you'll gain a few real friends.

8. Ignore the people they love.

In the same way no one lying on his or her death bed says, "I really wish I'd spent more time at work," I don't know anyone who has lost, say, his or her dad and then said, "I'm sad, but you know, I really do feel like I spent enough time with him." Everyone wants more time with his or her folks--when it's too late.

Your parents know you, and they still love you. Call them. They miss you. And though you may have forgotten it, you miss them.

9. Wait.

Franklin Delano Roosevelt was only partly right. True, "The only thing we have to fear is fear itself," but when you get down to it, a better quote might be, "The only thing we have to fear is ourselves."

Why? We're all afraid. We're afraid of what might or might not happen. We're afraid of what we can't change. We're afraid of what we won't be able to do. We're afraid of how others might perceive us.

We're afraid.

And that makes it easy to hesitate, to wait for the right moment, to decide we need to think a little longer or do some more research or explore a few more alternatives.

Meanwhile, days, weeks, months, and even years pass us by.

And so do our dreams.

Don't let your fears hold you back. Whatever you've been planning, whatever you've imagined, whatever you've dreamed of, get started on it today. If you want to start a business, take the first step. If you want to change careers, take the first step. If you want to expand or enter a new market or design new products or services, take the first step. Put your fears aside and get started. Do something. Do anything.

Today is precious. Once tomorrow comes, today is gone forever. Today is the most precious asset we all own. Wasting time is one thing it makes perfect sense to fear.