If you read a lot of fitness articles, you’ll read that it takes three weeks to establish an exercise habit.

It took me fifteen months.

Somewhere in the annals of time, I suspect, some motivational writer made an off-the-cuff assertion that it takes “three weeks” to establish a “habit.” I’m sure this is not empirical. What sort of habit? It takes me roughly two days to establish a habit of eating half a giant chocolate bar every afternoon.

But it went viral, much like the self-help gurus’ distortion of early psychologist William James’ statements a hundred years ago about human potential, that morphed into the myth that we use only “ten percent of our brains.” We all use our whole brains. So don’t send me an inspirational email with a cute Powerpoint slideshow with puppies and sunsets in it telling me this.

But I digress.

Six months into my new exercise plan in 2006, it began to get more difficult to continue. I was following a plan in a book, and it was a good plan, with three or four days a week combining strength and cardio (HIIT and steady-state). I’d moved in with my boyfriend and we set up my treadmill and dumbbells in the basement, and even a TV for me to watch. I’d lost seven or eight pounds and my body was already looking very different. But I was getting bored with the same plan, the same schedule, the same exercises, all the time. Getting through my workouts began to feel forced, as if I was an unwilling victim of a taskmaster who was also me.

What was different this time — with the five-year goal — is that I became aware I was having a problem, instead of zoning out, making excuses, and stopping.

My solution ended up being to join a gym in January 2007, which I’d budgeted for, and then to buy a discounted package of forty personal trainer visits that I had to use within a year, which I hadn’t. I realize many people would not be in a position to make that choice. I dipped into savings to do so, with quite a bit of buyer’s remorse after the fact. It wasn’t the first time I’d thrown money at my fitness issues, and it had never helped before.

But I’d talked at length to the XSport Fitness sales guy about my frustrations and doubts, and he went ahead and set me up with the head trainer, a knowledgeable and encouraging 26-year-old guy named Mark, blonde, short, and compact. Mark set up a schedule where he strength trained me for an hour at 5:00 PM on Wednesday and Friday, and then he’d put me on the elliptical machine for another forty minutes. He asked me to commit to one additional group class at the club, and I chose Spinning class on Mondays at 6:00 PM. I always showed up, even though that instructor was a psycho Freddie Mercury lookalike who made us stand on the pedals and barely hold the handlebars until our quads failed, and yelled into the mic about our poor form and lack of seriousness. I liked Spinning class anyway, because the physical sensation was the most like the running I used to do.

It helped my motivation right away, because all I had to do personally was drive myself to the club and put on my workout clothes — then I could put myself in someone else’s hands! Originally, I was convinced I couldn’t work out after work; I was always so exhausted. But I found that it was my mind that was exhausted, and my body was actually okay. I also learned that I could work out despite lacking sleep, as long as it was only a day or two and not chronic. These were valuable lessons that still help me be consistent today.

Eventually, Mark was promoted to management, and I was shuffled through a couple of less experienced female trainers, though they were educated and provided the outside accountability I needed. And I think this is why it worked for me. In the five-factor model of personality, I’m pathologically off the charts on the scale of “conscientiousness.” This means I would never cancel at the last minute or not show up. The club was running a pretty lax show and I could’ve done those things without penalty, but I’d made an appointment and a commitment, and that triggered my innate follow-through.

By fall of 2007, I was at the end of my training sessions. I could have re-upped, but now that I no longer had appointments scheduled with trainers, frankly I was looking forward to some freedom for a change. This was during the period I was, improbably, on that long weight plateau — I’d started training at 147 pounds in January, ended in September or October at 147 pounds, and would still be at 147 pounds until the next summer! — and I was feeling somewhat disappointed in this outcome of all that money and hard work. I knew I needed a plan, but what I wanted was a break. But then, something weird and unexpected happened.

I would leave work as usual — by five o’clock now, since I had been all year, instead of staying until seven like I did before I exercised — and I would find myself driving over to the gym. Then, because I was already there, I’d go in. Then, because I might as well do something while I was there, I’d do a full-body strength routine with the machines and free weight exercises I’d learned. Then, because everyone knows you always follow weights with cardio, I’d get on the elliptical or stationary bike or rowing machine for another thirty or forty minutes.

It was a habit.