Iíve been amazed at how a good run in the morning affects my attitude all day, in a positive way. In my case, it seems illogical.

Iím not a morning person. If I had no demands on my schedule, I would fall asleep around 4 a.m. and wake around 10 a.m. Thatís just my normal internal clock. Six hours is exactly the number of hours I like to sleep, and thatís exactly the time frame I prefer to get them in.

So under normal circumstances, wake me before 10 a.m. and youíre likely to get the moody version of me - the person who feels robbed of the ideal sleeping schedule and now must carry on through the day as if it really didnít matter when it very much did.

Yet over the past three months, four times a week I set my alarm clock for some ungodly early morning hour, drag myself out of bed, strap on my shoes, drive to a trail and run.

And I love it. Somehow, I feel accomplished, like "Gee, Iím not even supposed to be awake, and look what Iíve already done today!"

If things donít go well at work? "Hey, at least I ran 3 miles today."

Issues with the family? "Oh well, at least I ran 3 miles today."

A friend cancels plans I've been looking forward to? "Eh, at least I ran 3 miles today."

I come home from the trail coated in sweat and maybe a little sore, and it doesn't even bother me that I've yet to put in my 10-hour work day. Sometimes I run my 3 miles then go home and mow the lawn before I hop in the shower.

Now, Iíve heard of the term "runnerís high" before, although Iím not sure feeling accomplished is the same thing. Still, Iím content to call it that for lack of a better phrase because I did "run" and my spirits are pretty "high" as a result.

When I Google "runnerís high" it seems a lot of stories attribute it to very long distances. But as a new runner for whom 4 or 5 miles is an exhausting achievement, maybe the effect is the same.

Either way, itís an interesting concept, the idea that something physically happens to your body during an intense workout that floods you with positive feelings.

"Runnerís high" is a phrase that we use to describe the feelings of psychological well-being that are associated quite often with long-duration, rhythmic-type exercise," Dr. Cedric Bryant, chief science officer for the American Council on Exercise, told WebMD for this story:†http://www.webmd.com/fitness-exercise/features/runners-high-is-it-for-real#1.

What causes the feeling on a biological level, however, apparently is still just a guess.

"For a long time, people believed the answer lay within the whole endorphin argument -- with long-duration exercise you release endorphins, which have a morphine-like effect on the body and therefore may be responsible for the feelings of well-being," Bryant said.

But that theory fails in some studies when the effects of endorphins were blocked chemically, but people still experienced that high, he said.

So researchers looked at other neurotransmitters that could affect a personís mood, like dopamine and serotonin. Those things are known to help reduce depression and are released in higher concentrations during exercise.

Another theory relates to body temperature, that perhaps the elevation in body temperature affects the hypothalamus, which may indirectly affect mood.

And as it turns out, you donít have to run a marathon to reach that runnerís high.

Some studies have found that euphoric feeling described by people who are active for 30 minutes or more at a moderate intensity.

Well heck, that's me! Whether the feeling comes from a physical change or some emotional reaction, I guess it doesn't matter. Nor does it matter if I'm mixing apples and oranges, and the runner's high isn't the same as just feeling really good about having done something transformative. But whatever I'm feeling, it's real enough.

- Paula