I do think pursuing opportunities to increase your capacity to do good is an important part of being good as a person. Ability works too, definitely, as in my book power is not much more than ability to carry out an action, whatever that may be. A transition that is possible to you, but maybe not others.
I suppose I would also swap the binary idea of being or not being a good person, for a continuous measure of “goodness”. In fact, instead of saying that a person is good or bad to some degree, I think it makes sense to evaluate the morality of each act individually—how good or bad was that act of yours? As all people carry out good and bad acts each day.
And if we evaluate the moral value of acts, then having an ability to carry out these acts in the first place becomes even more important. We are all born under different circumstances, with different abilities. But it is also true for many of us (perhaps most) that we can develop ourselves, increase our capacity to help others.
Just launched my own version of a calibration test here—https://calibration.lazdini.lv/ it is pretty much identical to http://confidence.success-equation.com/ except the questions should be different each time you visit the site, allowing for regular calibration/recalibration. Questions are retrieved from the free API provided by https://opentdb.com/.