Praying might help you free your mind of worry and in so doing think up a way to actually help the other person. But praying for someone else cannot possibly do any good unless you also take some action. In fact it can do just the opposite. In fact, there's a study, quoted in the NYTimes, that says praying for post operative heart patients statistically created more stress and worse outcomes, Once they hear that people are praying for them, they tend to think they must be much sicker than they thought they were, which adds to their stress. So, long story short, it's really best never to pray for other people.