Living in God's will. Part IV - Prosperity?

Some people say that one way we can know we are in God's will, is when we are prospering, since God brings blessing.  Let's have a quick look at this verse:  

"I can do everything through him that gives me strength"

This is the kind of verse that sports people often put on their gear or person when competing (eg. Evander Holyfield) and others preach from or quote from to make a declaration that the world is their oyster.  

Taking a look at its context lets look at the 2 verses before

Php 4:11b-13

"I have learned to be content whatever the circumstances. I know what it is to be in need and I know what it is to have plenty. I have learned the secret of being content in any and every situation, whether well fed or hungry, whether living in plenty or in want.  I can do all things though him who gives me strength"

So prosperity alone is not a guide.  Also check Jesus: the son of man has no place to rest his head...