Categorical imperative requires reason to dictate the act we are morally obligated to do, one which is motivated by adherence to the consistent principle which could be applied to all and any rational agent. This deontological ethical distinguishes between the moral doctrines of right from that of virtue. Where the first is driven externally to the actor, the other is internal and concerned with ends.
Circumscribing what end is - Kant required of a rational human being that he makes the object of his elective will his end. Kant is very much concerned with ends which at the same time are duties and not with ends due to impulses of the senses or subjective/technical ends. The former are for him objective/moral ends and rests on a priori principles.
For Kant, a rational human being is a moral person, fully conscious of his moral duty or duties and deriving deliberate decisions using the metaphysical moral framework. The mere possession of capacity for rationality is nothing compared to its exercise and fulfillment in action.
All of this is built upon the foundation of good will or universal good or good unqualified/unconditional and autonomous which he laid down in Groundwork. The Kantian moral system emphasize the performance of moral duty motivated by a priori principle recognized by reason and not from desire of expected consequence or emotional attachment or aversion because duty or end based on sensual inclinations is conditional. It is the role of reason to give fruition to a good will.1
Duty and right are the motivations of good will; aspects of good will, if you may.
Groundwork portrays the search for the supreme principle of morality. It sets aside matters that are recognizable by the reader from everyday experience and conceives its subject to be a priori and metaphysical. I think Kant expect the reader to do the exercise of applying the test and criteria he laid down.
Kant's recognition of will as separate from reason shows his recognition of actions and ends which are derived from will alone or that derived from a conjunction of will and reason. Reason alone cannot achieve the intended result. Obviously, "will" alone can only get conditional results unlike a real concurrence of will and reason or the good will.
Groundwork does not really explain the manner and contents Kant conceives an a priori principles system to have. He takes this matter for granted and leaves too much room for the reader to speculate. Nothing in it describes what metaphysical structure duties should have.
The universality test as a method of weighing duties is Kant's significant contribution to moral reasoning but Kant barely seemed to use it in his writings. Kant's method is to determine the universal law of morality applicable to all rational beings at all cases.2 He must have conceived of his writings as a workbook with which readers must work and apply as they go along; a veritable inter-active philosophical work for that matter.
For Kant, the duties to perfect one's self and to promote the happiness of others are moral motives and ends in themselves, including that to avoid suicide and self-mutilation. The supreme moral index of autonomous good will identified in Groundwork is broken down in MetaMorals into specific moral duties.
For Kant, doing one's duty is its own incentive, even for wide obligations such