Scratchpad: Motivations to Do Good
To like to do X implies that doing X provides a sense of enjoyment or pleasure. To want to do X because one likes to do X means that doing X is motivated by the joy or pleasure received by doing X. There are certainly many other kinds of motivations for doing something. One might engage in the activity in order to receive financial gain, increase security, inflict pain, achieve social standing, and so on.
Now, if one likes doing something, can one help being motivated to do it by the fact that one likes it? There may certainly be other additional motivations, but I don't think these will somehow "crowd out" the motivation of joy or pleasure, and one can certainly be motivated by a multitude of factors.
But what of doing good? I think one could justifiably say that one has an obligation to do good by definition. That is, a moral act is an act obligated by a moral code, and the moral code defines what is good, which is just another way of saying that the moral code obligates one to do good. To put it one more way, one is obligated to do good for its own sake. But, does this obligation preclude doing good for other additional reasons?
Consider three hypothetical people: the first does good begrudgingly, because he has to but wishing he didn't; the second does good neutrally, without feeling anything for or against the act; the third does good enthusiastically and thus enjoys it (for, is it possible to have enthusiasm for something one doesn't enjoy?). It seems somewhat intuitive to say that the first is less praiseworthy than the other two, and the third more praiseworthy. So, one could say that it's better to like doing good than to do good without liking it. But, one usually wants to do what one likes, so it seems that doing good may also be motivated by the joy or pleasure received by performing the act. After all, "doing good is its own reward"---the reward being the joy received from doing good.
Now, some may recoil at the idea that doing good can be motivated by the pleasure received by performing the act; for, shouldn't good be done for its own sake? And yet, taking joy in doing good (doing good enthusiastically) is better than doing good begrudgingly or neutrally. These two ideas can be reconciled by taking into consideration that doing good can be an expression of love, or it can be motivated by other factors.
Just as in doing good, an enthusiastic loving act is more praiseworthy than one done neutrally or begrudgingly (if such an act could be called loving at all). Thus, one can (and should) take pleasure in loving acts, and one will therefore be motivated in some degree by the joy or pleasure obtained in performing the act. However, the loving act is not motivated solely by the pleasure received, but also by the love (affection, care, concern) one has for the recipient. As such, the motivation for the act is not merely inwardly focused, and thus the act is not selfish.
Similarly, if one does good merely for the pleasure received, without love, one could justifiably be held culpable of a morally reproachable inward focus. So, it isn't the pursuit of pleasure itself that denigrates an otherwise good act, but performing the act without outwardly focused love. As such, a good act may therefore (must therefore) be motivated of itself, by the joy or pleasure received in performing it, and with love for the recipient.
Now, what of other possible motivations? Since doing good ought to entail love, one could approach this question by determining whether loving acts may have additional motivations. Is an act any less loving if there are secondary motivations? My first inclination is to say yes, but the reason for this doesn't seem immediately obvious. Why should other motivations somehow decrease the genuine love expressed by an act? If this is the case, then performing good acts with self-interested motivations could be justifiable provided that the acts are also accompanied by a genuine love for the recipient and the additional desire to perform the acts for their own sake and for the joy or pleasure obtained by doing good.