Prayer... a very subjective action to many people. Some people believe in it; some people don't.
However, we often forgotten that prayer is just an act of requesting, not demanding.
Sometimes your prayer may not be answered; sometimes your prayer is answered in a different way that you cannot even possibly imagined.
When you pray for strength, do you think God make you strong immediately? or given you a chance to be strong?
When you pray for happiness, do you think God make you happy immediately? or given you a chance to be happy?
When your prayers are not answered, just be patient...maybe God has another plan for you...and always remember to pray...until something happen =]