Good question. Well doing practical things like charity work is good and it pleases God. But this is only "treating the symptoms of the disease and is not a cure". It's like getting medicine from a doctor that only treats the immediate pain but does nothing to remove the causes. Praying is the cure! It clears our bad karma so that we will not have to suffer anymore. God is clever, very clever, because He created everyone on this earth for His pleasure (this world is a drama) AND created a get-out route. Most people continue to be reborn again and again to continue suffering again and again. They never take the get-out route! That is why we pray.