'Ought' Implies 'Can' But How Capable Are We?

I've heard the saying "'ought' implies 'can'". I take that to mean "If you say that I ought to do something, I have to be able to do it." This saying makes a lot of sense, but it can be a deceptive truth, because if we are unaware of the saying, if we instead think "'ought' is when reality demands something of me", then we may well find that we "can" do much more than we otherwise would have thought we could. If we focus a lot on how "'ought' implies 'can'", if we just don't want to do what reality demands of us, we fail to develop the capabilities and thus say "Well, I can't, so I'm not obligated to do anything."

Is ought something we ask of people, and so it would be unfair to ask too much of them? Or is the failure to do what we ought something we impose on reality, and it is unfair to reality to not do what is really called for? The answer to both questions is yes. I guess the way to practically sort this out (one way, at least) is to approach life as though you always have a duty to external reality, and you find out the limits of your "can" by pushing yourself further in your pursuit of fulfilling that duty. You learn that you "can't" by trying as hard as you can and being unable -- and to really know that limit, you have to keep trying even after you think you're unable, until you are unable to try.

If you don't want to do what reality calls for, you will find that you "can't" much sooner than if you do. If you do, you will be more correct whenever you reach the point of judging yourself as "can't".