How many times in grade school did you hear a teacher, administrator or whoever say something along the lines of "a good attitude is the key to success," or "not with that attitude?" or some variation. It occurs to me that your attitude is a symptom, a derivative feature, of your inner existence, like a fever and cough is a symptom of a cold. Whether you have a serious issue in your life, from home problems to depression, anxiety, etc., or not, you're attitude is your own personality filtered through that lived experience or hardship, a change in attitude is a symptom of that stress. It would be like a cancer patient asking if the doctor thinks they'll live and hearing "not with a white blood cell count like that!"
This is just a stray train of thought, what do you guys think?
This seems like predestination Calvanism crap to me. Look, the only way anyone anywhere ever becomes good at something is by doing it, being bad at it and then continuing to do it despite being bad at it. If you become frustrated or embarrassed with your crappy work and quit that means you have a bad attitude. This is normal. Everyone and I mean EVERYONE has a bad attitude at some point in their lives. Perseverance is a learned skill it is not innate to your soul and neither is the frustration or lack of motivation that leads to quitting. So no, attitude is not like your white blood cell count, you do have the ability to change it. Its not as simple as I'm making it sound, but your teacher is right to tell you that attitude is key to success.
I also want to address your point about personality. You seem to think personality is static? People's personalities change a lot over the years as they learn, experience and grow older. It's generally called becoming more mature.
I am worried that OP has depression. As someone who has been diagnosed with both: I'm not saying that its your fault when your depression gets the better of you, but I do want you to know that you still have the ability to make your life better. Thinking that you are powerless in this situation is the worst thing in the world. Luckily it is not true. Depression is something that can be coped with and managed to the point where it almost goes away. I had a depressive episode that lasted 5 years. After slowly working for several minor victories in my life (painfully slow, this was done over 5 years) I found myself becoming more confident. Eventually I realized that I didn't feel depressed anymore. I had energy to do things, want to do things and I liked myself. I'm still learning how to deal with the anxiety but I'm making progress. I used to be at a point where I couldn't invite friends to hangout because I had such bad social anxiety. Now its no problem. Still bad at approaching new people tho.
Anyways, I know it hurts to think about all the opportunities you've missed out on because of depression, but you need to know that you're not doomed to miss out on everything.
EDIT: The last part isn't necessarily directed at OP since Idk his mental health. Just towards anyone who is depressed.