I don't have a problem with the idea that God will bless us if we follow His commandments. However, the type of prosperity that Joel Osteen and others preach about is far above what God has promised. They seem to claim that if we are truly faithful, hardships will disappear and we will be be rich beyond our dreams, and that is just not Scriptural.
Nothing can be "above" what God has promised.
If it weren't like that, then it really is all by works, and God is nothing more than Santa Claus (perish the thought).
As far as hardships, I know that the only hardships He brings into my life are to do a greater good later, for His glory and my good. :)