In my opinion, Job and Tobit are figures whose suffering made them care about other people.
What do I mean by that? Didn't they already care for others? Wasn't Job an advocate for the poor and oppressed (Job 30-31)? Did not Tobit go out of his way to bury his fellow Israelites and to give alms (Tobit 1-2; 4:6-11)?
Yes, but why did they do those good deeds? I think it was because they wanted to earn God's favor by doing the right thing. Job offered sacrifices to God on behalf of his children because they might have cursed God in their hearts (Job 1:4-5). He was trying to stay on God's good side so that nothing bad would happen to his family. Not surprisingly, there was a rabbinic view that Job only served God out of fear, not love (Mishnah Sotah 5:5). And Job also had a deep-down contempt for the poor people he was trying to help, seeing them as riffraff (Job 30). He probably helped them because he was paternalistic, or out of a desire to get God's goodies by obeying the rules.
Tobit brags a lot about his righteous deeds. His very first words in the book are: "I, Tobit, walked in the ways of truth and righteousness all the days of my life. I performed many acts of charity for my kindred and my people who had gone with me in exile to Nineveh in the land of the Assyrians" (Tobit 1:3 NRSV). And he tells about how God gave him favor in the eyes of the Assyrian king Shalmaneser because he was mindful of God with all of his heart: unlike most Jews in Assyria, Tobit avoided the unclean food of the Gentiles (Tobit 1:10-13). Tobit never really says why he was so religiously scrupulous. But he seems to mention divine rewards every time he talks about his actions (see Tobit 4:6-11).
Both were floored when they got hit with hard times. Job initially refused to curse God, but he came to the point where he expressed a lot of bitter disappointment with him, to the consternation of his self-righteous friends. Regarding Tobit, after he was blinded in his attempt to do the right thing, he tried his best to believe that God was fair--that God was someone who rewarded the righteous and punished the wicked. But he struggled with despair and wanted to die (Tobit 3:1-6; 4:6-11; 5:10).
You see a lot of "Why me?" in the speeches of Job and Tobit. They wonder why they're suffering, especially after they had diligently obeyed God's rules. Eventually, however, they come to think about people other than themselves. There are times when Job stops thinking about his own suffering and asks God why he allows pain for anyone, not just him. He discusses rich people who throw folks off their land, making them homeless and hungry in the desert (Job 24). Job wonders why such oppressors die in a state of happiness and prosperity (Job 21). Why doesn't God punish them? Job probably never asked these questions while he was prosperous. He just focused on obeying the rules and reaping the benefits of his good deeds. Prior to his suffering, he never stopped to ask why the world was so unfair.
And Tobit is rather self-centered until he finally gets his sight back. Tobit sends his son Tobiah on a mission, and God works it out so that Tobiah helps (and marries) a woman who's troubled by a demon, and returns with material that can heal his father's blindness. God had a plan for Tobit's blindness, which helped not just Tobit but others as well. In Tobit 13, we see that Tobit comes to think beyond himself, for he looks to the day when God will restore and bless Israel and convert the Gentiles. Tobit's experience of God in his suffering leads him to have a universal vision.
Job and Tobit arrive at a deeper understanding of God as a result of their suffering. Job says that he always heard things about God, but now he sees God face-to-face (Job 42:5). And Tobit probably was familiar with the writings of the prophets prior to his blindness, since he quotes Amos 8:10 in Tobit 2:6. But he arrived at a genuine appreciation for God's activity in the world as a result of his suffering. The prophets came alive for him after that experience. He was no longer just thinking about God and Tobit--he was praising God for what he was doing in the world.
My purpose in this post is not to say, "Okay, you need to arrive at a level of authentic obedience from the heart, rather than acting like Job and Tobit before their suffering." We do what we do, with the motivations that we have. Rules will not change that fact. I personally can't wave a magic wand and make myself suddenly have the right motivation. What I am saying is that God can use our experiences to give us a different outlook on things, one that transcends our usual focus on self (see Character, McCain's "Inaccuracies").