I had a long conversion with a good friend about being told as children that we could do anything if we worked hard enough and then being disappointed as adults when things don't pan out.
I really like and agree with your optimistic twist. There was never anything I could have done to be an Olympic marathoner. There was no wrong choice in my past, no lack of motivation. I just don't have the physiology. The "you can achieve anything if you put your mind to it" mantra can make physiology feel like a personal failing, but it isn't. Understanding I have limits and knowing it's ok to have those limits really helps.