> And if you are not doing "your best", it's still bringing value.

I don't think most people would disagree with this, at least I don't. But if you don't have an excuse then you're failing to meet your potential, which you shouldn't be happy with (or at least as happy as if you had). "Doing your best" or "achieving your potential" is a virtue. It's like when people tell you to practice kindness, or generosity, or forgiveness, or whatever. They are principals that we've decided are worth striving to meet (there is room for disagreement on that but I think it's outside the scope of this conversation).

This isn't to say you have to always live up to these principals, we are human and can't be expected to behave perfectly. I don't always react kindly when someone cuts me off in traffic, and I've been known to hold a grudge on occasion, but I still believe kindness and forgiveness are virtues worth striving for. You don't have to practice a virtue 100% of the time to still believe it is worthwhile, we don't need to throw it away completely because it's impossible to always live up to, we simply must do our best.

"Do your best" doesn't mean you need to reach the absolute peak of your performance or don't bother doing it at all. Circumstances will dictate what "your best" looks like. If fact, this is the most common use of the phrase. When you know you're capable of better, but circumstances dictate you can't at the moment, you "do your best". For example:

> Can't go to the gym for 2 hours? Go for 45 minutes.

In my opinion, that IS doing your best. If you actually can't put in your full workout, but still manage to get one in, you did your best. You aren't failing to do your best because circumstances dictate you can't hit peak performance. If you had no excuse and just decided to half ass your workout anyway, that would be failing to do your best. That's what should be avoided.