Always do your best.
It’s the best advice I have to give, for myself or for anyone else.
It’s basic: the rule applies to any situation.
It’s straightforward: you do know when you are or are not doing your best, moment by moment.
It’s nonjudgmental: only you can know if you’re doing your best. You can encourage others to try harder, but it would be silly to think you know what “their best” looks like better than they do.
If you believe “best” to be some Absolute Moral Law, then do your best to follow it.
If you believe “best” to be some Utilitarian Outcome, then do your best to make that happen.
Either way, you’ll fall short sometimes. That’s ok. Notice where you failed and keep doing your best.
Your best today may not be the same as your best tomorrow; some days, you can’t do all the good you’d like. That’s ok too. If your best today is really only to get out of bed or clean your room, then that’s all you need to do. Tomorrow maybe you’ll be ready to tackle that big problem. Do the best you can in the meantime.
And once you accept that “best” includes figuring out what is “best”, then you’re on your way to Meta Level morality too. Part of doing your best is figuring out the best “best” to do. Learn. Watch others doing their best and think about whether you can do better by their example.
Doing your best doesn’t mean doing each thing perfectly. You might naively start out with the heuristic “try really hard at everything I do.” This works okay for a minute, but I think you find out pretty quickly that you’re tired, and that you waste energy on trivialities that you should save for important things. Since you’re trying your best, you decide to modify your simple heuristic and allocate your effort more wisely. It’s ok to half-ass it with everything you’ve got. Doing your best implies that you are paying attention to what works and what doesn’t.
This is the closest thing I know of to a completely general moral rule. And as such, it is sufficiently vague that you could use it to justify anything if you didn’t know better.
But you do know better. You know when you’re not doing your best. Pay attention to that feeling, and do better next time. Keep doing better until you are doing your best, then work to make tomorrow’s best better than yesterday’s.
Or, in the words of Plato:
And what is good, Phaedrus? And what is not good? Need we ask anyone to tell us these things?
Sorry if this post seems like I’m overexplaining a simple concept. I’m just doing my best.