Researchers have spent a lot of time studying people who think positively. It turns out that an optimistic attitude helps us be happier, more successful, and healthier. Optimism can protect against depression — even for people who are at risk for it. An optimistic outlook makes people more resistant to stress.The best thing about optimism is you can learn it, even if your outlook tends to be more pessimistic.You've probably heard people who tend to see the faults in everything called "…