The three biggest mistakes you're making at work (probably without realising.)

You work hard, you meet your targets, you get along with your boss… and yet you still keep missing out on the promotions and opportunities at work you think you deserve.

It could be that your manager is a jerk – or it could be that you’re making one or more common work mistakes without even realising it.

While these mistakes are easy to make, the good news is that they’re also easy to rectify and overcome once you’re aware you’re guilty of them. Here are the three biggest mistakes you could be making at work:

1. Promising things you can’t deliver

It’s happened to us all. Your manager asks you how far off you are from finishing a task. You say 20 minutes knowing it will actually be more like 30, but hoping she won’t notice or mind it took an extra 10 minutes.

But this simple act of over-promising and under-delivering is a huge mistake, says self-awareness expert Dr Travis Bradberry.

Dr Bradberry heads up TalentSmart, a company that provides emotional intelligence data to employers. In his piece published in the Huffington Post, the ‘Emotional Intelligence 2.0‘ coauthor explains that not only does promising something you can’t deliver add extra pressure and stress to your day, but it also makes you look bad.

“If you promise to do something ridiculously fast and you miss the deadline by a little bit, you’ll likely think that you did a good job because you still delivered quickly,” he writes. Exactly.

“But the moment you promise something to someone, they expect nothing less. You end up looking terrible when you fall short.”

This harmful habit is easy to fix once you’re aware you’re doing it – simply give your boss a realistic expectation, even if you don’t think that’s what they want to hear. They’ll be far happier that you gave them exactly want you said you would, when you said you’d do it.

2. Hitting a slump and not doing anything about it

We can’t all love our jobs – that’s a reality. But if day in day out you walk into a job that you loathe, or are simply bored of, then you’re giving yourself a massive handicap on the happiness stakes.

This does not mean you quit your job the moment you notice you’re not as excited to be there as you once were. There are ways to overcome your work slump, says finance writer Asit Sharma.

Sharma, who writes for The Motley Fool – an investment advice website – says it’s not uncommon to hit a prolonged period of “why am I here?” thinking at some point in your career.

This is a sign, he says, that you need to make a change. It sounds obvious, but it’s a sign too many people ignore.

Missed out on a job? There’s a better way to handle that rejection. Post continues.

“You may be stuck in a position in which you’ve stopped growing, or you may have realised that your organisation doesn’t properly value you,” he suggests.

“Or maybe it’s you, and your heart, intellect, and ambitions just aren’t vested in what for someone else would be a perfectly good job.”

Once you realise this slump cannot go on – “it’s not fair to you or your co-workers,” says Sharma – you can figure out the root cause and address it.

“Try to fix the conditions under your control that are defeating your enthusiasm, and if you can’t, it may be time to move on.”

“If it’s not feasible to leave in a short time frame, begin researching and planning your next steps. Just don’t accept a slump as your permanent fate.”

Complaining about your job

We all complain about work right? Well, actually while it might seem ubiquitous, not everyone complains about their job, and certainly, not everyone does it in front of their co-workers.

Dr Bradberry says that bosses and colleagues notice negativity in the workplace, and by constantly complaining, you can forge a, well, negative reputation for yourself.

“You were hired to make your boss’s and your team’s jobs easier, not harder,” the job performance expert points out.

“People who spread negativity through their department and complain about the work or other people complicate things for everyone else.

“If people always have to tiptoe around you so as not to dislodge that massive chip on your shoulder, they are unlikely to be willing to do it for very long.”

Dr Bradberry adds: “Bosses are quick to catch on to naysayers who drag down morale, and they know that there are always enthusiastic replacements waiting just around the corner.”

This might seem unfair, especially if you’re a talented, hard worker. The reality is though, you might actually love your job, but if all you do is complain about it, that’s not the message your employer is going to receive.

Try only bringing up workplace critiques through the proper channels where they can be constructive, and save the venting for after hours with your partner or non-work friends.

Did you realise you were making a huge mistake at work? Please share the lesson you learned in the comments below.