Ace is still loving the big skies of Montana, but he seems a little less smitten with the long trails.

One of the wondrous things about Missoula is -- almost any direction you head -- you are out in the countryside within minutes, with easy access to prime hiking trails that wind through the mountains.

Ace and my girlfriend Tamara didn't waste any time getting started on them.

First, they climbed up to the giant white “M” on the side of Mount Sentinel, which abuts the University of Montana campus.

I passed on that one, because I had some work to do and -- though only 1.5 miles round trip -- it has 13 switchbacks and looks pretty steep. And remember, the air is thinner here.

From my perspective (which is that of overweight smoker) it looked more like a three-day trip than the leisurely hour long hike it’s usually billed as. I will get to it soon, though.

The next day, while I worked, they headed to Blue Mountain Recreation Area, south of town, and logged another four miles or so.

The next day, a Saturday, I joined in and all three of us hiked the Woods Gulch Trail in the Rattlesnake National Recreation Area -- well, at least we did until we took a wrong turn onto some other trail and went several miles before backtracking.

Later, Ace – as much as he seemed to enjoy the four-hour hike -- seemed totally worn out, so exhausted that he didn't budge again all night.

On Sunday, I came to my office on campus after dropping Ace and Tamara off for another hike -- a planned six-mile trek across up Mount Sentinel and through Hellgate Canyon, then down a trail that returns to campus.

They'd done maybe a quarter of a mile, I was told later, when Ace rebelled, refusing to go any higher. Off the leash (you can get away with that here), he turned around, came down the dusty mountain and found some cool grass in which to collapse.

His body language was quite clear, and it was saying two words: I'm done.

Perhaps it was just too much too soon -- a hiking overdose, so to speak -- which would prove how right I am right to take this healthy, exercising, clean living stuff in moderation, so as not to shock my system too severely.

After all, back in Baltimore, Ace and I were used to walking once or twice a day to Riverside Park, then back home -- a mere six blocks, and even then we often stopped on the way for a beer at the corner bar, called The Idle Hour.

It might just be that I raised a dog more interested in bar hopping than trail blazing.

More likely, we just overdid it (well, not me). Maybe he's still getting used to the fact that, despite all the fascinating sights and smells on the mountainsides, there are no taverns along the trail -- and that, here in Montana, his hours are a little less idle.