Golf seems to be a harder sport than I realised, at least for 70 year olds like me. I entered our club's Scratch Championship yesterday, which was two 18 hole rounds on the same day. I was OK for the first 27 holes, but after that my legs hurt, my back hurt, my shoulders hurt, and pretty much everything else hurt. My drives which are normally 210-220 yards and pretty straight came down to about 150 yards, usually low weak hooks, so my game in general suffered. For the last 3 or 4 holes I could hardly even walk! 
