SOMETIMES, I WONDER why I do the things I do.

I wonder why I think I can carry a canoe on my shoulders for a mile to get to a spring pond where ultimately, I will fish for three hours with nary a trout brought to hand.

I wonder why I know that my best buddy sitting across from me is holding a possible straight flush and yet, I try to bluff him out with a hand that is no more than a king high.

I wonder about lots of things like that, but in the winter while pushing myself through 20 miles of up and down cross-country ski trails while training to get ready for skiing 34 miles in the American Birkebeiner at an age when one would think I would know better, I really wonder.

This winter is no different, except that after completing 20 of North America’s largest and greatest cross-country ski race, I have finally gotten a wee bit smarter and will only be skiing the 18-mile Kortelopet companion race to the Birkie.

Sometimes, I wonder why I gave up downhill skiing where I got to sit in the comfort of a chairlift to reach the top of a mountain before allowing simple gravity to get me to the bottom, in exchange for sweating and swearing my way up hill after hill on cross-country skis with only the fading strength of old arms and legs to get me to the top.

I wonder, but really the answer is simple. I love doing it. At times, that love gets a little weaker by the hill, but in the end, when I climb to the top of the International Bridge spanning Highway 63 in Hayward, look up three blocks further to the big, bright finish line banner of the Birkie, I know that I do it because, well, just because I can.

The Birkie became a part of my life in 1984. Goaded by Birkie veterans whose smiles I learned six hours and 32 minutes after the starting gun went off had nothing but pure evil behind them, I finished my first Birkie.

Going down hills meant snowplowing for all you were worth with the back ends of your skis pushed into ridges of icy snow crystals outside what tracks were left on an ice-hardened course. I took my first header when someone in the process of falling, whipped me across both legs with a ski pole, sending me flying with her.

I fell just once more. That happened when I started to skid around a corner at the bottom of a hill just about 8 kilometers from the finish. I wouldn’t have fallen, but a sudden cramp hit me like a sharp knife through hot butter, sending me into a crumpled, near-weeping hulk.

I thought my first Birkie was over right then and there, but somehow, I managed to rub out the cramp, get back on my skis and slowly slog my way to the finish.

Once there, I swore on Uncle Fester’s grave I would never put myself through it again. But because I found I would move up two starting waves because of my finish time and with a couple dollops of Crown for encouragement, I found myself at the start line again the next year.

I improved my finish time by almost an hour and a half, and the rest became history.

I no longer wonder why I spend so many hours of my life each winter on skis come hell or high water, 50 above or 30 below, 3 feet of snow or barely 6 inches. Cross-country skiing and the Birkie, now the Kortelopet, is a part of my DNA.

In my addled brain I have come to the rational decision to stick with the shorter Kortelopet for the rest of my days, except I have in a corner of that addled brain that I will do the full Birkie at least once more.

In three more years, I will reach a new age class, the 75-79 group and I’m thinking I might be able to pull off a Top 10 finish if I do the Birkie itself, given that there are usually 15 or fewer men of that age doing the Birkie.

My ultimate goal and now, you really have to wonder just how addled my brain can be, I am shooting for skiing and completing the Birkie at age 89, which would guarantee me not only a first-place finish in my age group, but also set a new record for the oldest person ever to finish the Birkie. The current record was set by an 88-year-old guy a few years ago.

Seriously though, I know I will keep skiing for as long as my body lets me. There is a rhythm to skiing cross-country that beckons me again and again.

The peace and quiet of the woods is perhaps the greatest draw. Seeing fresh wolf tracks crossing a trail as I did last week, spotting a great gray owl perched in a tree as I did a few winters ago or just enjoying a winter sun setting behind the stark, bare branches of oaks lining a ridge keep me on skis.

The camaraderie of spending a long weekend with friends of a like mind who have shared your Birkebeiners with you for 30 years or more make me forget about wondering why I do what I do when it comes to doing the Birkie.

I won’t be wondering at all when I line up this year for the start of the Kortelopet. I’ll know exactly why I am there and I’ll be glad I’m there.