This story truly resonates with me as I am also first generation. I came to USA on my own, with $700 in my pocket and a partial athletic scholarship (played a D1 team sport). After I finished my undergrad and the sports were gone (in an organized form at least) I also struggled a bit. Unlike you, I made that step and got into grad school. That was probably one of the best decisions I've ever made (even though it didn't feel like at the moment). The main reason I've managed to accomplish everything in my life was primarily because of being involved in sports and being competitive in anything that I do, whether it is sports, academia, work or anything else. I believe that a healthy dose of competitive drive is what makes you a better self as you always strive for improvements. It certainly made me a better athlete and a better student.

Another thing that you mentioned is that you fell off the track a bit and you are never going to be in the shape you were in college. Trust me on this one, you'll hit your prime between 28 and 32 years old. That's when you could potentially be your strongest and fastest. And staying in shape is a lot easier than getting in shape. I was lucky that my grad school allowed me a lot of flexibility and I was still able to play my sport on a semi-professional level even after college. Try to find a group/community of like-minded people who share your passion for running. That will be your "hobby" and will fulfill multiple things that you are missing in life at the moment (e.g. staying in shape and competing).

Having said that, my "quarter life crisis" (or one third life crisis if you will) is kicking-in harder this this time around as I am in my mid 30s and my athleticism is slowly going away. Being in the middle of pandemic is not helping either. I used to be extremely agile, with a 40" vertical jump but this has been on a steady decline due to age and mileage and all the restrictions imposed on sports and gatherings. Still learning how to deal with it.