I'm sorry, but "positive thinking" is not the Good News, nor has the Good News been preached by the Dalai Lama. The Good News is that we, who were separated from God and under his wrath because of our sins, have been saved by God through the death and resurection of the perfect, sinless Jesus Christ, who died to pay the price of our sins. The Good News has NOTHING to do with the "power of positive thinking", and that's not what Jesus preached.
I have no idea if that is what Joel Osteen preaches, as I haven't read this book yet (I was just reading the reviews). I do know, however, that what you said in your comment about Jesus's message being about "the power of positive thinking" is flat out wrong, and I wanted to set the record straight so that your review doesn't confuse anyone. Real, Biblical Christianity is and has always been about Jesus being our savior and saving us from our sins, which is something no amount of positive thinking could have ever done.