Let me start by being completely honest. Self-worth is something that I personally have had my own struggles with, whether it's that feeling of not being good enough for something or comparing myself to others and feeling like I don't measure up to them.
Not only is this harmful to one's own health (mental and possibly physical), but it also blocks them from receiving a positive flow of energy and sometimes things.
Self-worth is the sense of one's own value or worth as a person. In other words how you view yourself.
Never take your self-worth for granted, because in the end, it's all you have.
And it's not just about the toxicity of a relationship (romantic or otherwise), but everything else that comes along with it, good or bad. It's enjoying the little things and the memories you make together. It's laughing and having a good time. But MOST importantly, it's having the ability to leave if it becomes so toxic that it's filled with more bad than good.
Toxic relationships can be hard to define and in some ways, a relationship (yours or someone else's) you think is, others may not. It's all in the eye of the beholder. For me, it wasn't until a friend of mine who was on the outside of the relationship pointed out how toxic it truly was. But by that point, the damage was done and it took a while for me to get back to the person I was before it.
So, in short, your opinion on yourself is the one that matters most, no one else's. It's so easy for people to look into the mirror and pick out the things they hate about themselves or to look at someone else and wish they had whatever they had (good job, slimmer waist, longer hair, etc.). DON'T do it. You don't have to be wonderful like them -- you can be wonderful as you.
So how do you know (in the instance of a relationship, romantic or not) when it's at that point?
You start to feel bad about things that once made you happy. You lose motivation for things you once loved. This is why knowing your self-worth is SO important and means everything.
As humans, we must know the importance of our worth. If someone makes you feel bad about yourself, they're not the right person for you. Setting high goals and even higher standards can help immensely, but so can putting yourself first once in a while and asking "Is what is happening here good for me?".
Dr. Suess once said:
"Today you are you, that is truer than true. There is no one alive who is youer than you."
And that is so important for someone who struggles with self-worth or thinking that they aren't enough or even that they need to follow the crowd to "fit in" and be like everyone else.
Life is too short to be involved with toxic people who bring you down. Do not be afraid to stand up for yourself and even walk away if necessary.
And most importantly do not let anyone or anything define your worth.