Well done!! You've made me feel a bit better about the fact that I can only do 35 seconds. I'm 64 and not at all fit, but I started exercising three weeks ago, three times a week. I could only hold the plank for 20 seconds at first, but doing repetitions has helped. Onward and upwards. The biggest surprise reading this was that someone insane held it for over 9 hours!! Ye Gods.