I've done a Tough Mudder. I've completed an Ironman-length triathlon. I've run in a circle for 77 miles.

Not until this week, however, have I seriously considered quitting an activity, or been so glad I didn't. Then again, not until this week has a fitness pursuit pushed me all the way to the brink of consciousness.

Yes, I'm talking of course about Bikram Yoga, a.k.a. Hot Yoga. There, it isn't the exercise itself that's so demanding. Hard exercise I can handle. It's the environment.

I don't care how fit you are. You might even be one of those people who thrives in the heat. One hundred and five degrees is not a comfortable temperature in which to practice Yoga.

It wasn't for me, certainly. Not for 90 minutes. My objective as a first-timer at Bikram Yoga in Shaker Heights ($15, bikramcle.com) was simply to stay in the room, and let me say that at times, that goal seemed almost totally unrealistic.

Never in my life have I been so tempted to flee. At times during the class, recommended to me by a member of the Cleveland Orchestra, the air-conditioned lobby visible through a glass door in the studio took on the elusive appeal of an oasis in the desert.

And I'm not even talking about the actual poses, some of which I actually attempted. Simply sitting in a chair in that kind of heat for 90 minutes would have been an accomplishment in its own right.

Had the class taken place in normal weather conditions, I probably would have loved it. In particular, I enjoyed how this form, developed out of Hatha Yoga by Bikram Choudhury in the 1970s, was free of spirituality and performed without such distractions as incense and music. Even the lights remained on until the restful conclusion.

I also appreciated the physicality and thoroughness of it. Despite the intense heat, this was probably the most active Yoga class I've ever taken, comprised of poses targeting every joint and muscle group I can think of, as well as a fair number of balance maneuvers. No wonder those who practice it say it keeps them young.

Unfortunately, I can't offer many specifics. Most of my brain power during class went to preserving vital functions, not memory, and my sweat would have soaked any piece of paper on which I might have taken notes just as surely as it did the beach towel I'd laid over my mat.

This much, though, I can tell you: the results were fantastic. No matter that I spent almost as much time sitting down, trying not to faint, as I did in actual motion. Afterwards, after I'd cooled down and drank a liter of water, I felt as energized, clean and limber as I have in ages. I wasn't even lethargic the following day.

Yoga in general has never sat well with me. I know it's great, and that I, more than just about anyone, stand to benefit from its merits. Flexibility, though, has never been a priority for me, and my weakness at yoga only makes me less interested in pursuing it.

Still, I could see doing Bikram again. Not on a daily basis, perhaps, but again. Maybe even several more times. I imagine, in that sense, Bikram Yoga is like running: what at first seems crazy soon becomes mandatory.