It's often said that luck is where opportunity and preparation meet. However, I believe that finding great success in life requires one more thing: the willingness to say YES when an opportunity arrives.

Believe me, I know that it can be a lot easier to say NO when an opportunity looks too daunting, or when you feel like you've already pushed yourself as hard as you can. But by saying YES, the opportunity will be yours. If instead you say NO, then you'll miss out -- perhaps forever.

So instead of saying NO, take every opportunity to say YES. Here's why.

1. The next opportunity might change your life.

Sometimes I'm tempted to say NO when a new work opportunity presents itself. However, I know that the next opportunity might be the one that changes my life forever. So I do everything possible to say YES.

2. It pays to push yourself just a little harder.

While we're all busy and often feel pushed to the limit, we can always squeeze a little more out of our lives. Remember: If you get up just one hour earlier each day, you'll have 15 extra days to work with every year.

3. People like people who are agreeable.

People like other people who are agreeable and open rather than disagreeable and closed. Who would you rather work with?

4. People don't like naysayers.

People who constantly look at the negative side of life are no fun to be around. Don't be one of those.

5. YES is for optimists.

Optimists get more done and they're more successful than pessimists. Just say YES, and you can be an optimist too.

6. You'll build your network.

When you say YES and open yourself up to meeting new people, you'll grow your network and your business reach. This can lead to all sorts of new opportunities -- and success -- that you never imagined.

7. You'll be more successful -- and happier.

Don't believe me? Then consider the words of Google executive chairman Eric Schmidt: "Find a way to say yes to things. Say yes to invitations to a new country. Say yes to meeting new friends. Say yes to learning a new language, picking up a new sport. Yes is how you get your first job, and your next job. Yes is how you find your spouse, and even your kids. Even if it's a bit edgy, a bit out of your comfort zone, saying yes means you will do something new, meet someone new and make a difference in your life, and likely in others' lives as well... Yes is a tiny word that can do big things. Say it often."