Instead she finished with "...committing any crime you can't retire on". It was a game-changer for me. This advice...had context. It wasn't a absolute "no", nor did it rely solely on experiences I didn't have. It extended on experiences I _did_ have into a broader area.
Throughout most of my teenage years I avoided all the worst situations that peer pressure was steering me towards, not because I suddenly properly calculated the risks - I could no more visualize the impact on my life that any kind of conviction would have than I could before - but because I was better weighing the _gains_. Instead of "doing this will prevent me from losing ranking in my social hierarchy" it was "doing this will not gain me material improvement". Instead of "if I fail I will get in trouble" it was "I will be disappointing because I tried, regardless of success".
Eventually, of course, I built my own ethics structure about why crime/rudeness/unnecessary risk-taking were undesirable, but this one statement gave me time to do so that I might not have had.
I highly recommend it to all parents.