Be careful with self improvement, if you spend too much time thinking about it you'll always feel like you're never good enough to get what you want. Here's a personal anecdote of how I thought that I wasn't good enough for an opportunity, and I ended up getting something better than what I had asked for.

A little background: I got fired from my last job. It was a good job, but I was terrible at it and it destroyed my sense of competency and self worth. Every day that I went there I felt like a failure.

Things have gone better at my new job. I was promoted recently, but even in that position I felt behind where I should be now. About a month back I saw an opening for an internal position that I really wanted, and even though I felt underqualified I applied anyway. A few weeks went by without hearing anything, so I assumed that I had no chance. Eventually I got an interview, and I thought that I answered OK, but not well enough to get the position. Surprisingly, I had a follow up interview, which wasn't so much an interview as the hiring manager telling me that I really impressed on the prior interview (with his boss) and that I was their top candidate. I was elated.

A few days passed without hearing anything from them, when I get an email from someone high up in the food chain (I'll call him Big Wig) in my department asking if I could call him later that day. He said that he heard about my application to that other position, and he asked if I would at least entertain the idea of meeting with one of his direct reports (Big Wig Jr) about a position on his team that hadn't been posted yet.

I met with Big Wig Jr a few days after, and the position he described was exactly what I wanted. I was offered the position, but the catch was that it would be a lateral move in terms of rank and salary, whereas the position that I applied to would have been a bump in both. I decided to give it a day to think what I wanted, job satisfaction or money. I chose both.

When I received an offer letter from the original position, I thought of asking Big Wig if he could do anything to match the salary. I felt nervous about the idea, "don't ask for more money, that will make it harder for the people who outrank you and it will make them upset" my inner faggot told me, as if I should feel guilty for asking for money at a job. I told my inner faggot that he doesn't get a vote in my future, and I forwarded the letter to Big Wig asking if he could match it. A few hours went by and Big Wig Jr tells me that they can bump the salary to match, and that I have the opportunity for a promotion in a few months. I'm happy as fuck.

TLDR: Wasn't satisfied with my job, applied for a position I didn't think that I was qualified for, then through a stroke of luck I leveraged that position to make more money at a job that I wanted more. You'd be surprised what you can get if you take a chance.

EDIT: I should have clarified that I applied for an internal position in a different department, and the position that I took was within my current department. I did not apply externally and I had communicated with my manager through the whole process.