You may wonder if anyone will even notice if you don't demonstrate professional behavior at work. As long as you do your job well, who cares? It turns out your boss, customers, and co-workers do. They will notice if you lack this quality and it could have severe consequences for your career. To discount the importance of professionalism would be a big mistake. It can affect your chances for advancement or even the ability to keep your job.

How can you show your professionalism? Follow these dos and don'ts:

Make It a Priority to Be on Time

When you arrive late for work or meetings, it gives your boss and co-workers the impression you don't care about your job and, if it affects them, it's like saying you don't value their time. Pay attention to the clock. Set alarms if you have to. Show up at least a few minutes before you are supposed to start work and return from your breaks on time.

Don't Be a Grump

Leave your bad mood at the door when you come to work. We all have days when we aren't feeling our best. Remember not to take it out on your boss, your co-workers, and especially your customers. If work is the thing that is causing your bad mood, it may be time to think about quitting your job.

If that isn't a good option for you right now, find a way to make the best of the situation until it is.

Dress Appropriately

Whether you have to dress up for work or you can wear more casual clothes, your appearance should always be neat and clean. A wrinkled suit looks no better than a ripped pair of jeans does.

Choose the type of clothing your employer requires. If there isn't a dress code, pick attire that is the norm for your place of employment.  Save flip-flops, shorts, and tank tops for the weekends, along with clothes that are better suited for a night out at a club.

Watch Your Mouth

Swearing, cursing, or cussing—whatever you call it—has no place in most workplaces. Unless you know it is okay in yours, refrain from using foul language, particularly if those who you might offend are present. Here's a good rule of thumb to follow: If you wouldn't say it to your grandmother, don't say it at work.

Offer Assistance to Your Colleagues

A true professional is willing to help his or her co-workers when they are overburdened or facing a challenge at work. He or she isn't afraid to share knowledge, opinions, or simply an extra pair of hands. One person's success reflects well on everyone in his or her workplace.

It is important not to be too pushy, however. If your colleague rejects your offer, don't push it. He or she may prefer to work alone.

Don't Gossip

While you may be tempted to tell your cubicle neighbors what you heard about Suzy or Sam down in accounting, gossiping makes you look like a middle school student. If you know something you simply must share, tell someone who has nothing to do with your workplace, like your sister, mother, or best friend.

Try to Stay Positive

Negativity is contagious. If you complain incessantly about your workplace, it will bring others down. Your boss certainly will not appreciate a drop in morale among his or her employees. That does not mean you shouldn't speak up about things you think are wrong. If you see something that should be fixed, give your boss feedback along with a plan for how to make improvements.