Let's define codependency
In a nutshell... you're codependent when you base your self-worth on how much you help others. There's nothing wrong with wanting to help people, BUT there is a line with helping TOO much and it'll hurt the person you're trying to help AND you'll end up hurt as well.
As always I don't expect you to be able to distinguish where that line is all on your own so I'm here to help. A good identifier of if you're codependent is how helping others makes you feel. When you help people do you feel resentment for helping them? Or do you feel like you were trapped or guilt tripped into helping them? Or do you feel guilty for NOT helping? Like I keep saying, if you do not WANT to help them solely because you're compassionate and will enjoy it, you're probably codependent.
For example, if you find yourself only going out and drinking with your best friend because that's what they wanted to do even though you were feeling a movie and going to bed early and THEN you feel resentment towards them afterward, or if you're afraid they won't like you anymore if you say no... you're codependent.
Another example would be if your adult child or parent frequently asks you for money and you say yes telling yourself it's because you're a kind person, but really you find yourself screening their calls because you know they're going to ask you for money and you feel that resentment creeping in... you're codependent.
OR if your relationship is only stable when you feel like your partner needs you. Again... you're putting your self-worth into another person needing you, or into their well being, or how much they think you've helped them.
"How empty of me to be so full of you"
Why this is SUPER dangerous
There are SO many reasons tbh. You can end up enabling bad behavior. Your self-esteem is based on others perceptions of you which means it can go down and there's nothing you'll be able to do about it. You can put a negative strain on your relationships. You can start resenting people because you're masking your feelings and not stating how you really feel.
What is so hard about codependency is that it blurs the line between compassion and "doing too much". This topic is taught in trauma and addiction therapy to families AND patients because it can lead to compulsive behaviors, anxiety attacks, chronic depression, apathy, suicidal thoughts and loss of self. I cannot stress this enough... if you're feeling ANY of these things PLEASE really think about why and seek therapy because we ALL have codependent tendencies.
How to recognize and break away from codependency
In other words "okay, I've realized I have these tendencies... what do I do?"
The first thing you should do is set boundaries. I wrote a post on Why Setting Boundaries is Important that can explain more on how to do this. Start really thinking about how these behaviors make you feel. Notice when you feel resentment and stop doing it. I stopped going out with my friend who only wanted to drink because I didn't want to and our friendship was worth more than a night out. Resentment ruins friendships so I stopped saying yes to things I didn't want to do because I actually cared about the friendship enough to say no.
The second thing is to put focus back on yourself. Being a self-less person is not an admirable trait. You NEED to address your needs before anyone else's. Ask yourself how you would feel about doing something before you do it. Again this goes back into self-awareness that I feel like I talk about all the time. You are the MOST IMPORTANT person in your life! Write that on a sticky note and stick it to your mirror because if you fail to put yourself first people are going to take advantage of you, and you're going to ruin relationships because you resent them and it's not fair to those who are important to you.
The third thing is to LET THE FUCK GO. You need to detach from everyone else's life, drink a margarita, sit in the quiet, and meditate. It's also codependent to try to run other people's lives. This is the one I struggle with the most (I always think I know what's best for everyone in my life). The real selfless act is allowing other people to live their life and make their own mistakes and I PROMISE you your relationships will be so much stronger. You hate when other people butt in and tell you how to live your life, so don't do it to them.
Repeat after me:
If I keep from meddling with people,
they take care of themselves
If I keep from commanding people,
they behave themselves
If I keep from preaching at people,
they improve themselves,
If I keep from imposing on people,
they BECOME themselves.
(The founder or Taoism)