HIT THE WALL with a big bang today!!! Went out at 6AM to do 24k on a new route. Have fairly easily done 20K a couple of weeks ago - but today underestimated the hills along this route, the heat 25C and the humidity 85%+ and didn't carry/drink enough water . Got to 19K and had to call the ambulance (my wife) to come and get me!!!! Have never run to exhaustion before - now I know what it feels like!!!