Mine isn't very funny. Spur of the moment decision to go walking when the wife was away. Got up at stupid o'clock, drove to mid wales, arrived before a september sunrise. No-one knew where I was. Walked too far, ran out of energy, food and water. Made a navigation error and lost an awful lot of height on my route, and then realised how tired i was when I had to start climbing again, into a stiff headwind. So tired I could only walk about 20 yards at a time, and dehydrated, so I couldn't add up the four coins in my wallet. Lost the path. No mobile phone signal of course. Made it back to the car as the sun set, and got safely home.
I learned a lot of things that day. Mainly about what not to do.
I'm a much better outdoorsman now as a result of that day.
best way to avoid that is to always carry a milbanks bag, a metal mug and something to boil the water with (honey stove is great for that) and you should never be without water, unless your in a desert, but in the uk that wont be a problem.
TJ