"Want" seems insufficiently reflective, it suggests present opinion on the matter rather than an accurate estimate, whatever that turns out to be, and however well it can be known in practice (which is what I meant). To do as you should is to do the right thing (as opposed to the pebble-sorting thing, say).

To unpack a bit: there is this wanting/liking/approving distinction that already places "wanting" in the wrong corner, but even after that there is a level of reflection distinction between what more explicitly drives your behavior (or evaluation of your behavior) and how you would respond given more time and thought.