Let me begin by saying that I'm not a fan of "prosperity gospel" - the idea that because we are Christians we are entitled to any sort of material blessing above anyone else, or that faith has a strict correspondence to our finances. I've met people who were below the poverty line with strong faith, and know people who are wealthy who don't.
That being said, there is an element of truth in what leads to the prosperity gospel - that our faith impacts the quality of our life. So I was interested to read how that played out in Joel Osteen's Think Better, Live Better.
I was happy to see that a big part of the book didn't focus on success as being purely financial. In that case, I do think it's true that our faith affects our life. If we have a positive mindset, we are likely to be more content with what we have, which will give us a better life. If we have faith as Christians, we can lead a victorious life, using that faith to help us overcome struggles and temptations. There are still allusions to tangible terms of success, but the book is written with a very optimistic tone that makes it encouraging to read.