I'm 46. I went to a D1 School. I ran a 29:52 10,000 my sophomore year. I quit the team at the beginning of my junior year due to a number of factors, among them a personal tragedy (girlfriend's death) and I felt my coach didn't know very much about running (he was fat and said a lot of insensitive things and didn't care about us personally). I was emotionally messed up from the tragedy and a long way from home (1,500 miles). I could have benefitted from a mentor.
When I quit the team I never looked back. I was a music major and the extra time to practice was valuable. I couldn't stand the coach anymore but continued to run on my own, even up to now. I ran 70 miles per week through college after I quit, but never raced again.
For years and years it never bothered me that I quit, but for the last year or so it has been nagging at me, "How good could I have been?" I guess I will never know. Sometimes it gets to me a little. I see runners enjoying success, and I would really have liked to have gotten an All American certificate.
My whole college career was unsatisfying, and I had trouble with the director of my academic program. He had a drug problem and was an inconsistent, unpredictable person, and mean as hell (he went to jail twice for impaired driving during my time there). I had good friends socially, but my academic memories are not very good, and coupled with my running memories--not much to reminisce warmly about from my collegiate career (however, I did win 2 dual meet races).
I have a good wife and family now and an excellent career and I make a good living. Part of me still yearns for the experience of being in a group of runners doing a workout on the trails and being young and part of a group. Plus, the internet connects runners today. In my day, it was very difficult to find out about other runners, how they were running or even what they looked like so I could recognize them at big meets. Only the really famous runners (Craig Virgin, Mary Decker, Henry Rono, Al Salazar) got much press then.
This is my advice: Make sure your collegiate program is a good fit for you. Make sure the academic program is right first. If your major is petroleum engineering, understand why you are going to your particular school over another school. Know going in what your opportunities will be. Then make sure the coach, his philosophy, how he deals with people is a good fit as well.
I didn't have that good of a fit (went to the wrong school for both academics and running), but there was so much to know and understand going in that I was unaware of. No one in my family went to college before me, so I never got good advice. As a freshman I didn't even see an academic advisor to make sure I was taking the right classes. There are safeguards now to prevent that from happening, but back then I was really clueless. I was an A student with a pretty high SAT score, but I was still very naive and I made a lot of mistakes. Some of the mistakes were painful, and some of them were expensive.
Now I'm trying to grow old gracefully, stay fit, and I hope I never want to retire. I run a 40 minute 10K. I am a competent musician, but nothing is more fun than being on a trail in the middle of the woods, enjoying every step.