I know this feeling, and I want to tell you the story of how I overcame it.
I didn’t do particularly well at school - flunked maths and English, OK in the sciences, not much else.
I managed to get into college on a computer technology diploma, on the promise that I would attend night classes and retake maths, which I did (and got a decent grade), but I flunked college and dropped out after the first year of a 2 year course.
I then went on a government sponsored youth training scheme related to computing, which would probably have led to an apprenticeship in some technical role, but I screwed that up by stupidly following others into petty theft, but I was the one who got caught and blamed, and I got thrown off the course.
After being unemployed for 6 months, my father managed to get me a temporary job packing boxes in a warehouse. Not the career I had dreamed of. So much missed potential.
Long story short, I did that for quite a few years. I had given up thinking about opportunities and change, and development.
Then I met the woman I would marry. That changed me and I started looking for opportunities, and taking them. Over the course of many years, I worked up through various roles in Inventory control, then IT (which is incidentally where I had very first intended to go), then management and leadership.
Alongside that, I realised I had lists of ideas I wanted to pursue in my spare time, but that I was not really doing anything about them. I decided to start just doing things - trivial things - on the list, and I found that doing this made me really happy.
I started writing up these silly hobby activities on a website, and later, on a channel on YouTube and it’s now (after 15 years) grown to the point where it might become my full time occupation.
And I still love it - and it is the thing that gets me out of bed every day.
Moral of the story: It’s really common to regret missed opportunity, but you MUST NOT allow that regret to occupy your attention. It’s pointless (unless by thinking about it you will derive some useful insight on not repeating the mistake)
The opportunity that should occupy your mind is the NEXT one - the next opportunity you have to find; and if you can’t find it, create it for yourself. This is something you can choose to do. You choose - you don’t wait for it to choose you.
It’s not easy, and neither is it a quick fix for anything, but it is good.
Look forward, not back.