Steve I think you'd find this read interesting but i don't want to take away from SRF just add to its validity so i hope you don't mind me sharing more on Sufism in this section
"When we try to reason out what we should renounce and how we should practice renunciation, we should remember that no virtue is a virtue if it is forced upon someone who is incapable of it. A person upon whom a virtue is forced, who is forced to renounce, cannot make the right renunciation. No virtue which gives pain is a virtue. If it gives pain how can it be a virtue? A thing is called a virtue because it gives happiness; that which takes away happiness can never be a virtue. Renunciation is only rightly practiced by those who understand renunciation and are capable of practicing it. For instance, there may be a person with a loaf of bread who is traveling in a train and finds somebody who is hungry and in need of bread. He himself is hungry too, but he has only one piece of bread. If he thinks that it is his Dharma to give it away and be starving, but is unhappy about this, he would do better not to give it away, for then it would be no virtue. If he did this once, he would certainly not do it again another time as he suffered by it and the virtue brought him unhappiness. This virtue would never develop in his character. He alone is capable of renunciation who finds a greater satisfaction in seeing another eat his piece of bread than in eating it himself."
http://wahiduddin.net/mv2/VIIIa/VIIIa_1_13.htm
