"I'm not sure I can do this," I said to myself while climbing a few steps to take a practice ride for a zip line.

I was in northern Costa Rica, in the shadow of the country's majestic volcano Arenal. I was part of a group of about 25 tourists, ages 6-60, all fitted with helmets and industrial-strength harnesses, preparing for a zip line tour of the rain forest. As we waited for a practice run, there was laughing and joking in Dutch, French, Spanish and English.

But it was probably better that I didn't understand most of the jokes. I wasn't sure I was ready to laugh about possibly falling on my head. You could say I was a little nervous. And this was just for the six-second try-out. The real zip line experience was two hours long and much farther off the ground.

I realize that these days, a reluctance to embrace adventure tourism practically makes you an outlier. Experiences like parasailing, dog-sledding or trekking in the wilderness have become so commonplace that many travelers don't hesitate to embrace the latest thrill. But I'm not that type of person. I won't even let my 11-year-old get on a roller coaster, though he's pleaded for it. It's not just too high — it's also too fast, too much up and down, too much jerking around. I don't like my head spinning or my stomach leaping into my mouth.

But then we planned a trip to Costa Rica, where zip lining above the rain forest has become a standard part of the tourist experience. My husband refused to do it, but my son begged to try it. Friends and colleagues urged me to say yes, insisting it was safe and not unpleasant.

One friend, though, gave me pause. Like me, she's not fond of heights. Walking around New York City, where we live, she pointed up to a five-story brownstone and a 10-story building to show how high I could expect to fly. How did she feel about her own experience zip lining? "I didn't hate it," was all she said.

Now here I was, ready for my test run. A guide hooked me onto a double steel cable and showed me where to rest my right hand, encased in a kind of leather glove. The practice run was a little like traveling across a clothes line and about that far off the ground. The harness was wrapped snugly around my waist and thighs. I sat back, feet crossed, one hand on the cable, the other on the harness, and off I went. My son followed.

"Want to keep going?" I asked him, hoping he'd say no. But he nodded, determined. "Once you start, you have to keep going," I reminded him — and myself. There was no hiking trail back.

We got in a large wagon pulled by a pick-up truck up a mountain. As we rode, we were drenched by a warm, calming rain. We then hiked a little farther up to the first platform, one of about 15, with each cable line varying in height and length.

My son wanted me to go first. The guide hooked me to the cable and off I sailed. Flying above the emerald green rain forest might sound magical and serene, but at least to me, this was not. The metal hooks sliding against the cables made a loud, whizzing noise, like some kind of mutant tropical insect. I was sailing above the green treetops, yes, but also above the green viper snakes and the green basilisk lizards and the green walking stick insects and all the other creatures that give new meaning to the word camouflage.

Each time I was pushed off a platform to sail across the cable, I avoided looking down. Keeping my eyes on the next platform and the next guide waiting there helped staunch my fear — along with the knowledge that finishing each segment meant I was closer and closer to the end.

More than halfway through, I was fitted with a different harness. You can control your own speed by pressing down on one of the cables, but I was slowing myself down so much that I almost didn't reach the next platform. The new harness gave the guides more control.

Finally, we were done. My son loved it, calling it "heart-racing." He was happy to have spotted a howler monkey and asked if he could do it again.

I wasn't even tempted. "No," I said. I was just glad to have finished without panicking or pleading for a machete to hack my way through the tropical forest and back to civilization.

A few days later, another nervous tourist traveling with her family asked me about the experience. "Did you like it?" she asked.

She laughed when I couldn't answer. But the truth is, what I liked is that my son loved it.