Ditto the first sentence.

One imperfect, but applicable analogy: "emotions are a fuel, and reasoning should be the steering system"

I think it would be useful to emphasize that not letting the emotions govern applies to regret as well: Yeah, I did what I shouldn't have (or missed an opportunity), but now it's done and staying miserable helps noone, just makes me feel bad. Let's take it seriously and make the best of it (at least using it as a very important lesson), focusing on improving the future, not crying about the past.