I don't believe in prosperity theology, but I don't believe we should live miserably and starve ourselves either. The sinful power of human greed can be harnessed to do great things. The Bill and Melinda Gates Foundation is a good example of this.
The point of mortification is not to be miserable or starve, it's to remind ourselves we love Christ more than the thing we're giving up. Part of the point is to do something that would normally make us miserable and then to
not be miserable about it.
This is was written better than I ever could in the Imitation of Christ by St. Thomas à Kempis (one of the best Christian books ever written and one I'd recommend reading sometime):