7 Poisonous Beliefs That Make You Desperately Unhappy How happy you feel is in large part something you can control.

LinkedIn Influencer, Jeff Haden, published this post originally on LinkedIn.

All of us, at least once in a while, are unhappy.

But what if you're unhappy much of the time? In most cases the cause is not external. How happy you feel is in large part something you can control.

But not if…

You believe professional success will bring lasting fulfillment.

You can love your company but it will never love you back. (Cliché, sure, but true.) Another cliché, just as true: No person lying on his deathbed ever said, "I sure wish I had spent more time at work..."

Professional success, no matter how grand, is still fleeting.

Fulfillment comes from achieving something and knowing it will carry on: Raising great kids, being a part of a supportive extended family, knowing you have helped others and changed their lives for the better...

Work hard on business. Work just as hard on a few other things you can someday look back on with a different sense of pride.

Then you will to feel great both now and later.

You believe simply joining will create a sense of belonging.

Making connections with other people is easier than ever, and not just through social media. Joining alumni groups and professional organizations, wearing golf course polo shirts or college sweatshirts, putting a sticker with initials like "HH" on your car to announce to the world you summer at Hilton Head Island… many people try hard to show -- if only to themselves -- that they belong.

Most of those connections are superficial at best.

If your spouse passes away the alumni organization may send flowers. (Well, probably not.) If you lose your job a professional organization may send you a nifty guide to networking. (Well, probably not, but they will send you the invoice when it's time to renew your membership.) Anyone can buy, say, a University of VA sweatshirt. (It was on sale.)

The easier it is to join something the less it means to you. A true sense of belonging comes from giving, self-sacrifice, and effort.

To belong you must share a common experience — the tougher the experience, the better.

Related: 10 Qualities of Really Amazing Employees (LinkedIn)

Clicking a link lets you join; staying up all night with a crew loading trailers to meet an urgent ship date lets you belong. Sending a donation gets your name in a program; working in an over-crowded soup kitchen (something, to my discredit, I've never done) lets you belong to a group of people striving to make a difference.

Pick a group you want to belong to and do the work necessary to earn respect and trust.

A true sense of belonging gives you confidence, especially during tough times, and provides a sense of security and well-being even when you're by yourself -- because when you truly belong, you never feel alone.

You believe you can do everything.

Our parents were well intentioned but wrong: We can't be whatever we want to be. We can all achieve amazing things, but we can't do everything we set our minds to. Genetics, disposition, and luck play a part too.

The key is to know yourself and then work to be the best you can be based on your unique set of advantages and limitations.

Here's a non-business example. Say you decide you want to run a marathon. Fine -- with enough training almost anyone is capable. But say you're a guy who weighs a muscular 250 pounds and you want to finish in less than 2 hours and 30 minutes. That's just not going to happen; you're not made that way and the attempt will leave you discouraged, defeated, and unhappy.

But with the right approach you could probably bench 350 pounds, something the whippet-thin marathon runners will never do.

What you achieve isn't nearly as important as achieving something. Pick a goal you're suited for and go after it.

Doing something -- doing anything -- that most other people cannot or will not do will make you prouder, more fulfilled, and a lot happier.

You're afraid of who you really are.

None of us really likes how we look. So we try to hide who we really are with the right makeup and the right clothes and the occasional BMW.

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In the right setting and the right lighting... hey, we're happy.

But not at the gym. Or the beach. Or when we have to run to the grocery store but feel self-conscious because we're wearing ratty jeans and an old t-shirt and we haven't showered and we think everyone is staring at us.

So we spend considerable time each day avoiding any situation that makes us feel uncomfortable about how we look or act. And that makes us miserable.

In reality no one really cares how we look... except us. (And maybe our significant others, but they've already seen us at our worst so that particular Elvis has definitely left the building.)

So do this. Undress and stand in front of the mirror. (And don't do the hip-turn shoulder-twist move to make your waist look slimmer and your shoulders broader.)

Take a good look. That's who you are. Chances are you won't like what you see, but you'll probably also be surprised you don't look as bad as you suspected.

Then, if you don't like how you look, decide what you're willing to do about it and start doing it. (Just don't ever compare yourself to other people; your only goal is to be a better version of the current you.)

Or, if you aren't willing to do anything about how you look, that's fine too. Move on. Let it go. Stop worrying about how you look. Stop wasting energy on something you don't care enough about to fix.

Either way, remember that while the only person who really cares how you look is you, many people care about the things you do.

Looking good is fun. Doing good makes you happy.

You have no one to call at 3 a.m.

Years ago I lived in a house beside a river. Flooding from a hurricane put my house in the river. I had about an hour to move as much as I could and I called my friend Doug; I knew he would come, no questions asked.

Today, aside from family, I'm not sure whom I would feel comfortable calling.

I know you have lots of friends… but how many people do you feel comfortable calling in the middle of the night if you need help? How many people can you tell almost anything… and you know they won't laugh? How many people can you feel comfortable sitting with for a long time… without either of you speaking?

Most of us wear armor that protects us from insecurity. That armor also makes us lonely, and it's impossible to be happy when you're lonely.

Take off your armor and make some real friends. It's easier than it sounds, because other people long to make real friends too. Don't worry; they'll like the real you. And you'll like the real them.

And all of you will be much happier.

You believe structure is the same as control.

Most of what we do, especially professionally, is based on trying to maintain control: processes, guidelines, strategies… everything we plan and implement is designed to control the inherently uncontrollable and create a sense of security in a world filled with seemingly random occurrences. (Did I just get philosophical on you? Sorry.)

Eventually those efforts fall short, though, because structure never equals control. No matter how many guidelines we establish for ourselves, we often step outside them. (Otherwise we'd all be slim, trim, fit, and rich.) Budgets and diets and five-year plans fall apart and we get even more frustrated because we didn't achieve what we planned or hoped. To-do lists and comprehensive daily schedules are helpful, but you only make real progress towards a goal when it means something personal.

Decide what you really want to do and go after it. You'll feel a real sense of control because you really care.

And when you truly care -- about anything – you feel a lot happier.

You believe you no longer need to fail.

Most of us do everything we can to avoid failure. That's a natural instinct with an unnatural by-product: we start to lose the ability to question our decisions.

And we lose the ability to see ourselves from another person's point of view. The ability to work with and lead others is compromised when we lose perspective on what it's like to not have all the answers… and what it's like to make mistakes.

Related: 8 Reasons Interviewers Screw Up and Don't Hire the Best Candidate (LinkedIn)

So go out and fail, but not in the way you might think. Forget platitudes like, "In business, if you aren't failing you aren't trying." Business failures cost time and money that most of us don't have. (My guess is "Failure" doesn't appear as a line item in your operating budget.)

Instead fail at something outside of work. Pick something simple that doesn't take long and set a reach goal you know you won't reach. If you normally run two miles, try to run five. If you play a sport, play against people a lot better than you. If you must choose a business task, cold call ten prospects.

Whatever you choose to do, give it your all. Leave no room for excuses. Make sure you can only be judged on your merits – and that you will be found wanting.

Why? Failure isn't defeating. Failure is motivating.

Plus failure provides a healthy dose of perspective, helps us be more tolerant and patient, and helps us remember that we're a lot like the people around us.

When you realize you aren't so different or "special" after all, it's a lot easier to be happy with the people around you -- and happy with yourself.