Most of us don't notice these words or phrases that make us look bad in a professional setting -- they often sneak up on us. If you say them, the key is to get in the habit of catching yourself "in the middle of the act" until you've trained your brain to not say them.

Here are five that will diminish your credibility and make you look really bad.

"Can't."

Your co-workers will dread hearing I can't because what they're translating that to be in their brains is I won't. Using can't conveys that you're not pulling your own weight, that you're unwilling to do what it takes to be part of the team and get the job done.

"It is what it is."

When you hear this empty phrase, you can bet the person who said it just dismissed something that is important or worthy of further discussion as the opposite. It's a sign of lazy discourse -- the unwillingness to engage others in deeper conversation to explore solutions, new ideas, or solve problems together. It may be what you say to your friends, but in a professional setting, it makes you look like a lazy thinker.

"I Guess."

There's your fast track to coming across as uncertain, indecisive and, therefore, incompetent in the eyes of your colleagues and superiors. Can you imagine making a presentation to an executive team or board of directors and answering a question for clarification with "I guess" and a shoulder shrug? Holy cow. You may have just lost your audience after saying it. The alternative? Even if you don't have all the facts, sound confident and certain about your answer or suggestion rather than feeling your way arouund in the dark. Words matter. And words with conviction and confidence matter even more when the stakes are high. 

"I'll Try."

You've heard or said it many times before: "I'll try to get that report to you by tomorrow." Or "I'll try and see if I can make the time for that meeting." What really comes across to the intuitive listener, who knows the truth, is this: I heard you but your request is not really a priority right now; I just can't be honest enough to tell it to your face. "I'll Try" creates doubt in the minds of others. And that doubt may cause you to be labeled the most unreliable person in the room.

"That's not my problem" or "not my job."

Even worse, the "no my yob" version with the south of the border accent. Hearing this shouted across the hall when you're asking for help or input on something important reveals an uncaring and detached attitude that screams "I'm not a team player." Granted, it doesn't mean "jump" and say yes just to please a colleague. If you don't have the time to deal with someone's request, articulate it tactfully and thoughtfully when expressing "no" in a way that doesn't make you look selfish or unconcerned.