Do you have trouble saying no to offers, requests, or proposals? Most people do. In a short but fascinating piece on Tony Robbins's website, the author argues that we have trouble saying no not because we have an innate need to please others but because many of us have been taught from a young age to take others' needs into consideration before our own.

That's an interesting perspective, and very possibly true. But whatever the reason, if saying no is difficult for you (and it certainly is for me) it's vitally important to get better at it. Because--although saying yes to things that truly inspire you can lead to an extraordinary life, saying yes when you should say no can drag you down, as well as everyone around you.

Next time someone asks you for something or to do something and you aren't sure you want to say yes, ask yourself if any of the following statements is true. If even one of them is, then say no. Consider it practice: The more often you say no, the easier it becomes. And the more time and resources you'll have to say yes to the things that really matter.

1. You're letting someone else choose for you when you should be choosing for yourself.

It can be really, really hard to resist someone who really, really wants you to do something. This happened to me recently when I was invited to return to a conference I attended last year. It was a great conference, and I got a lot out of it, but this year, because of other obligations, conflicting events, and too much recent travel, it really didn't fit my schedule. And the thought of dragging myself onto yet another airplane was seriously unappealing. 

Still, I like everyone at the company putting on the conference, and I consider the representative who invited me a friend. She invited me several times and made it very clear I'd be a special guest. And so I was trying to figure out some way that I could go.

Reading the piece on Robbins's site snapped me out of it. I asked myself if it really made sense to rearrange my schedule and take a trip I don't have time for just because someone I like a lot really, really wanted me to. Obviously, it didn't. So I sent my regrets. Maybe next year.

2. You're saying yes because you fear harming the relationship if you say no.

Relationships are important to all of us. If you care about a relationship and the other person truly needs your help (they've fallen out of a boat and have asked you to throw them a life preserver, for example), then you probably ought to say yes. 

But those situations are rare. Most of the time, doing what you're asked will help them, or make them more successful, or make things easier or more convenient for them. You are perfectly within your rights to consider how doing what they want will inconvenience or otherwise affect you.

If you decide you don't want to do it, it's your responsibility to say so, clearly and without waffling. It's often helpful (though not obligatory) to explain your reasons for saying no. None of that should damage the relationship. If it does, there was something wrong to begin with.

3. It's part of an unstated quid pro quo.

You may say yes because you believe that if you do, the other party will owe you a favor. And that means that the next time you ask them for something, they'll have to say yes just like you did.

The problem is that not everyone is playing from the same unwritten rule book. You could say yes at great inconvenience to yourself, and the other person might assume that you didn't mind or it wasn't any trouble. Then, when you ask for a favor in return, they may say no if it would inconvenience them. That will? harm the relationship--because you'll be royally ticked off.

So don't go there. Don't say yes to something you don't want because you're assuming an unstated promise that they'll say yes to the next thing you ask. 

On the other hand, a stated quid pro quo is perfectly fine. Sure, you'll cover for them this weekend if they will agree in advance to fill in for you when your sister gets married next month. That way, everything is above board, and both you and they can make an informed decision as to whether this is a good trade.

4. Saying yes would be wrong for both you and them.

This happened to me a couple of years ago when I was approached to spend a month in Uganda as a writing coach for graduate students in English. I really, really wanted to go. I've always wanted to see Africa, and it was an opportunity that seemed to require my particular skills (as opposed to, say, helping people build houses). 

At first, it looked like a great fit. But this was a very religious college that didn't fit with my own beliefs. I didn't mind--good writing is good writing--but as the job requirements evolved and the person running the program talked it out with me, it became clear to her that this was a bad idea. When she told me no, I was deeply disappointed, but also very grateful that she'd taken the time to really think things through, and consider my needs as well as her program's.

Saying no to something someone else really wants that isn't right for you or for them can be extremely difficult. Do it anyway. You'll be doing them a favor. And doing yourself one as well.