"Helen of Joy" is an orchestral piece from the Season 6 soundtrack.
Locke tells Helen that he went to Australia for a walkabout, but the tour did not let him attend. Locke screamed at the tour guide "Don't tell me what I can't do." Looking back though, he realizes there are things he can't do.
Locke tells Helen he's sick of imagining what life would be like if he could walk, including walking down the aisle with her. He'll see the new spinal surgeon he met if she insists, but he doesn't want to them to wait vainly for miracles, which don't exist. Helen rips apart the surgeon's business card. She says she believes in miracles though, and he's one of them.
The piece is a variation on Locke's flash sideways theme.