Not being a scientist or researcher, I cannot give a definative answer to the question. I have done some research on the web and have found some annecdotal type of opinions/studies, but it is really a hard thing to quantify.
I can only speak for myself that I really don't know how I would have been able to cope without the two you mentioned, and the third as well.
Periodically we see some guys on here that appear to be very bitter, and their posts just drip with sarcasm, anger, and bitterness. When some of these topics come up, or the R word is discussed, it becomes fairly obvious to me at least that the absence of these elements in their life has made coping very difficult for them.
Hope is certainly necessary for me, to keep on plugging along this route. Love for my family also is a big part of why I want to keep on going. Their love for me has made it all bearable as well.
It is a curious set of words that can really get some guys excited.