An example of how strange distances can be is a day when I was on a 155 yard par3 and meant to pick a 6Iron but mistakenly picked up a 9Iron (go ahead and laugh only time I've ever done that and certainly make sure I won't again).

Anyway, I proceeded to hit the shot thinking I had a 6 in my hand and hit a perfectly straight shot that fell just short of the green probably 140+ yards. I wondered why it fell so short after feeling great then looked down. I normally hit my 9Iron no more than 120 yards. Made me wonder how much the mental game can affect distance.