How we cite our quotes: (Book.Chapter.Bekker #s); all Bekker line numbers are approximate, since they are keyed to the original Greek.
Quote #7
If doing the noble and the shameful things is up to us, and similarly also not doing them—and this, as we saw, amounts to our being good or bad—it is, therefore, up to us to be decent or base. (3.5.1113b12-14)
There's no getting around it: Aristotle is 100% sure that we're personally responsible for our behavior. The proof of our virtue is in our actions, particularly because they are voluntary actions on our part. Unless they aren't.
This simple, positive declaration is served up alongside a lengthy discussion of voluntary and involuntary behavior. As it turns out, Aristotle does believe that it's possible to do bad things but not really be a bad person, depending on our ability to choose our actions. Being human is complicated.
Quote #8
For to boxers, the end—the crown and the honors—for the sake of which they fight is pleasant, but being struck is grievous and, given that they are made of flesh and blood, painful, as is all the exertion involved. And because there are many such painful things involved, the end for the sake of which boxers fight, being a small thing, appears not to be pleasant at all. (3.9.1117b1-5)
Aristotle isn't properly speaking of boxers (fighters, not underwear); he's really talking about courage. The illustration of the boxer who is willing to undergo something very unpleasant in order to have honor is a fair analogy for those who are brave in other situations. It also illustrates a paradox of virtue: though the ends may be something we long for (honor, money, etc), the path to glory can be miserable. We have to go against our understanding of virtue (as something pleasurable) in these cases to do the right things.
Quote #9
Thus it belongs to the liberal person more to give to whom he ought than to take from whom he ought or to refrain from taking from whom he ought not, since it belongs to virtue more to act well than to fare well and to do what is noble than not to do what is shameful. (4.1.1120a10-13)
Aristotle uses the example of "liberality" to outline the nature of virtue. The purpose of virtue is to motivate good actions (not to make money, gather honors, or have a great job). A truly virtuous person also acts in a positive rather than negative manner. So while it is good not to do things that are bad (i.e. have self-restraint), it's far better to actively do things that will benefit ourselves and our communities (i.e. be a moderate person).