You're speaking as if heaven and hell are the only rewards and punishments one can possibly receive. This is blatantly untrue.
Most often, evil deeds are punished. If you're caught lying to your friends all the time, they tend to leave you. If you're caught stealing from people, you're arrested and thrown in jail and sometimes even prison.
People are also rewarded for doing good all the time as well. Help a friend when they're down, and they might just return that favor. Cover for someone at work, and they may do the same for you when you need a day off.
Yes, many actions do go unrewarded and many others go unpunished. Sometimes, evil actions result in people being rewarded and sometimes good intentioned actions result in pain and suffering. It sucks, but that's reality. Does this mean we should just give up just because the world isn't perfect? Of course not.
If I see someone who needs to borrow 5 dollars for gas, do I refuse it to them saying, "Sorry, but many people need 5 dollars for gas. Since I can't give everyone who needs gas 5 dollars, I'm giving it to nobody since what's the point?" Of course not. The reality is, we try our best to help those we can.