Several weeks ago, I spent some time with friends of mine who happen to be a Rabbi & Rebbetzin. I was talking to them about my general lack of interest in orthodox judaism and how i have a hard time believing in some of the tenants. In any case, the conversation turned to davening (praying) and I said that I just have a hard time really caring about davening. I rarely go to shul during the week and generally go on shabbat, but more for social reasons than anything else.
About a month ago, I saw them again and the Rebbetzin lent me a book called Praying with Fire. It has 80-something 5-minute lessons that are meant to be read one at a time on a daily basis. She had heard good things about the book and thought it might help. I started to read it and have used it to really think about davening in general, the specific lessons for the day, and the words of the prayer i was saying at that specific time.
All this focussed thinking about prayer has led me to believe that prayer is virtually worthless. I don't believe in the power of prayer to change our lot with a higher power. I don't believe that prayer for someone helps them get better.
I have also come to realize, that like the belief in God which can't be proven with absolute certainty in either direction, people have a belief that prayer works. And what happens when the prayers are not answered? Well then, God just said no. So there is really no way to determine with any certainty that prayers do (or do not) work.
This is why I say prayer is "virtually" worthless. If prayer can help someone reflect and think about their life and where they can improve perhaps they will go beyond the prayer and put it into action. Along the same lines, I also think that it shows a caring side of someone when they pray for a sick person.
One side note about the book . . . If you are generally into prayer and just need that extra push or focus, then i would actually recommend this book.