It's curious why we use damaging words when we're talking about our own ability or about our willingness to do whatever it takes to achieve our goals.
When talking about ourselves, we tend to use words that diminish our ability and our belief in our capability. The impact these words have on the confidence others have in us is bad enough. It's worse that they affect the decisions we make and the actions we take.
The words we use, even if only in our head, say a lot about our attitude, and attitude is everything. In business, there are some things that are seemingly out of our control, like waiting for a potential client to pull the trigger for hiring us or for our bosses to finally deliver on that well-deserved promotion. But we can control the words we use, both spoken and unspoken, and in turn control our attitude. If your attitude about a situation is negative, then the words you use about the situation will also be and the likelihood of your actions and decision making around that situation will be in kind. And if the words you use have a negative or limiting connotation, even if our attitude is positive, those negative words can actually change our attitude in an adverse way.
Watch out for these:
Should/Shouldn't.  People are always telling us what we should or shouldn't do and we actually do the same thing to ourselves. The reality is, there is nothing you should or shouldn't do. What matters is what the right thing to do is and what you're willing to or want to do. When you say you should or shouldn't do something, you are making a value judgment about it, but that doesn't always mean you are making the right choice. Do the right thing. Always.
Have to. Let's get one thing straight right now. There are very few things you HAVE TO do in life and breathing is one of them. Anything you do because you HAVE TO is nothing more than your choice to do so because the alternative or the repercussions are not worth not doing it.
Can/Can't. You can? Great. But the question is, will you? The word 'can' is seemingly innocuous, but actually has a negative connotation. Think about it. Pick something you say you can do. Perhaps that's "I can land that client" or "I can get funding for my business." Now change the word from "can" to "will." Some say this is semantics but there is a big difference in how you think about the situation when you say you will versus saying you can. Can is not a definite but instead a possibility without action. There is nothing in can that says you will.
"Can't," on the other hand, is a copout. When you say you can't, you are saying there is no way or that you're not capable. Wrong. What you're really saying when you say "I can't" is "I won't." Own that and stop saying what that you can't do something because, in truth, you CAN do anything you want to, and you WILL do what you want to do.
Impossible. And speaking of "can't," can you imagine if the Wright Brothers said flying was impossible? (Well, the Wright Brothers weren't the first to fly, it was actually German-born, Gustave Whitehead.) But no matter who is credited, someone had to believe it was possible for it to be done. Once you convince yourself that something is possible, the rest is about finding a way and then taking action. Sure, you might fail many times before you find success, but saying that something is impossible makes it so. There has to be at least a small part of you that believes it is possible before you can make anything happen.
If you want to get out of your own way and stop holding yourself back, take action now. Start by watching out for how often the following six words creep into your thoughts and verbal communication. Consider whether or not the sentence containing these words is really the truth. Call yourself out, and then find a better way to think (or say) what you really mean.