I don't know how these guys do it but I've always thought it would an even more incredible rush than sky diving, free climbing, or just about anything else.
This dude was towed in on his wave, which is incredible still. The real animals are the ones who paddle into some of the giants at Jaws, Teahupo'o, Waimea, Mavericks, Todos Santos, or Cortes Bank. I can't remember who it was exactly (Dorian, Irons, somebody...) in the late 90's who paddled into what was believed to be the biggest wave ever successfully paddled into and surfed. Something like 80'. What an insane rush having to paddle into, stand up, get your speed going, and successfully ride the wave. Totally epic, and absolute stones of steel in those guys.