We each have within us some inner enemies that can quickly kill off our confidence. They drain our lives of potential and our purpose, and they fill us with deep regret. Left unchecked, they can unfortunately quickly erode our grandest plans and our noblest intentions.

See if you recognize any of these 12 confidence killers in your own life. If you do, you need to crush them now. Your future depends on it.

1. Feeling unworthy. Self-confidence comes when you feel worthy of who you are and what you're accomplishing--when you believe in yourself. When you think or say you're in any way not good enough, you're rejecting your own value. Combat these feelings by thinking of the things you appreciate about yourself.

2. Constantly overthinking. One of the worst enemies of confidence, overthinking leads to negativity. It twists things around, makes you worry, and makes everything appear so much worse than it actually is. When you give up overthinking you'll be amazed to see how many problems it caused.

3. Surrounded by negative people. Some people think being alone makes you lonely, but for me being surrounded by the wrong people--and negative people in particular--is far lonelier. Negative thinkers will never do you any good, so stay far from them.

4. Dramatizing everything. If you're scripting negativity and trouble in your mind, drama is bound to result. But it doesn't have to be that way. Whether you believe it or not, you have the power at any given moment to let go of the narrative so far and remind yourself that this is not how the story ends.

5. Telling yourself you're not smart enough. Nothing hurts more than trying your best and still not feeling smart enough. To regain your confidence, you have to literally tell yourself, "I am smart enough to succeed. I already know a lot, and what I don't know I will learn." Each of us is smart in what we know--we just have to acknowledge it.

6. Thinking that good things only happen to other people. Why do we always think the grass is greener on the other side? The truth is, if you were to get the baggage of others you would likely be glad to give it back. You never know what other people are carrying, being grateful for the good things you do have and be patient for the rest. Maybe it's your turn to be the good thing that happens to someone else right now.

7. Living in the past. What's done is done, as the old saying goes. We all have decisions we might undo if we had a choice, good times we took for granted, events we wish we could have avoided. You can't change the past, but find strength and hope in the fact that you can always change today.

8. Counting your failures. We all fail sometimes--some more than others. It doesn't make you unworthy or less intelligent. Remember, the only people who never fail are the ones who play it far too safe.

9. Measuring your mistakes. Regaining confidence after a mistake can be tough, but try to redefine the terms. If you want your confidence back, learn to treat your mistakes valuable lessons that you have learned and moved on from.

10. Sabotaging yourself. There are few things more self-defeating than negative talk or putting yourself down. Negative self-talk can be so pervasive that you can't even hear it any more. Shut down your inner voice of fear and negativity and unworthiness.

11. Comparing yourself to others. You will never believe in yourself as long as you're comparing yourself to someone else. Being kind and true to who you are--to your unique thoughts, ideas, actions, and beliefs--is as important as being kind and honest to others.

12. Being ungrateful. No matter how bad you have it, someone will be worse off; no matter how good you have it, someone will be doing better. Gratitude allows you to focus on what you do have instead of what you don't. It gives you the confidence to appreciate what's around you and the poise to pay attention to details you might overlook. Any time you need a boost, take an inventory of all the great things you have.

In short: Be positive, be true and forgiving with yourself, be grateful. That's the recipe for building self-confidence.

Published on: May 20, 2016
The opinions expressed here by Inc.com columnists are their own, not those of Inc.com.