None - triathletes are crazy!
None - but I'm going to do one this year.
Sprint
Olympic
ITU Long Distance ("double Olympic")
Half-Ironman
Ironman
"My predominant feeling is one of gratitude. I have loved and been loved;I have been given much and I have given something in return...Above all, I have been a sentient being, a thinking animal, on this beautiful planet, and that in itself has been an enormous privilege and an adventure." O. Sacks