I'm marginal with respect to the word "good," but there still might be some value in my story.
I started running seriously in the fall of my junior year at Princeton--not with the team, just on my own. I wasn't very good by any objective standard, but I lowered my 10K time from 42 to 37 over that winter and spring. In the summer between junior and senior year, I ran 40-45 mpw, my first sustained mileage. I actually imagined that I could walk on to the XC team in the fall of my senior. (I was rooming with guys on the team and got a contact high.)
That fall, coach Larry Ellis let me run one workout with the team, then made a face, shook his head, and said, "It's not going to happen." They were all holding 7:00 pace like it was a jog in the park, but it was a hard tempo for me.
So I kept running on my own--that year and for the next four years. I regularly ran sub-36 10Ks and sub-18:00 5Ks. I wasn't talentless, I just had no talent.
I ran a few marathons over the next several years. In 1983 I ran 2:53:30. Around that time I ran a couple of workouts with former team members I'd bumped into in NYC, and I could easily keep up. Ran a couple of 10-mile races just under 60.
Many years and several hundred races later, back into racing after a long break, I won the Alabama state 10-mile championship in the over-50 category. 6:55 pace or so. I won several local 5Ks outright with times around 19:30--and won money in both of them.
There's no moral to the story, except living well is the best revenge. There are many sports and pastimes that give great pleasure and satisfaction, even when you're not very good by any objective standards. You might even win a race or two, if you keep at it. I think I'm a good example of somebody who showed little or no potential early on but managed to leverage my way up to a place where I could actually (occasionally!) prevail, by virtue of smart training and sheer stick-to-it-iveness.