Second Wind -What is it and why won't it blow in?

Goal179

Hi all

Can someone tell me scientifically what a "second wind" actually is? I am getting exhausted during the first half of my workouts, but when my "Second wind" kicks in, I have a huge burst of energy and I can end them on a high note. My problem is, the second wind doesn't always kick in when I expect it to. Isn't it supposed to kick in at the same time each time you work out? Sometimes, it doesn't come until the very, very end of my workout. By then it's too late because I am already done. Help me understand what I need to do to make this come along a little sooner.

Achrya

It's an ability Warriors have that heals them when they drop below 35% HP.
http://www.wowhead.com/spell=29838/second-wind

Bebubble

The second wind, like many other exercise-induced "highs", is increasingly suspected of being purely psychological; it is claimed by some to be a by-product of the confidence and pride one gains by passing one's supposed limitations. Studies have found similar results when researchers have simply offered encouragement to subjects during exercise.

http://en.wikipedia.org/wiki/Second_wind