With happiness research so in vogue as of late, this corrective article by Robert Frank explaining that there's a difference between happiness and welfare is worth a read. As he explains, the human brain is astonishingly adaptable, and will tend to, after a bit, give lottery winners and paraplegics the same mix of moods they had before. So whether you're newly rich or freshly immobile, after a period of adjustment, if a researcher were to ask you how happy you were, it'll probably be about the same as it was before. That said, paraplegics still report they'd undergo a surgery with a large risk of death if it could restore their mobility*. So clearly they see a distinction between mood and welfare.
*On the other hand, some happiness researchers would argue this is just a function of our tendency to overestimate how things like better health or more money would improve our happiness. On the other other hand, very few of those researchers would likely shrug at the prospect of their own paralysis.
