Speeding at 45 miles per hour on a zip line, 250 feet above the ground through a lush rain forest — feet dangling, hair blowing, heart pounding. Racing across the waves at dusk on a catamaran in the Caribbean, wind rushing past your face and in your hair. Climbing, rowing and hiking. All things that get your heart pounding, your blood racing ... and your sex drive raring and ready to go.

I spent a couple days in St. Kitts last week. Nothing but sand, surf and adventure activities. That’s what got me thinking. It was amazing to me that the more the activity scared or challenged me, the more adventurous it was, the sexier I felt.

I’d never been zip lining before. Too scary. But I figured, when in Rome. So up I went. As I zipped down the line and through the trees, my heart was beating as fast as I was racing. Your face gets flushed. Your breathing gets heavy. The blood rushes through your body. (Kind of like the sensation you get from another activity I know of!) More than anything though, you feel empowered for getting in there and doing it. And I don’t know anything sexier than that.

You get the same high from hiking, especially when you go higher than you ever have. Or from running, especially when you go longer and faster than you ever have. Or from diving, especially if you’ve never been, or you’ve never been that deep. And you don’t have to be on a tropical island to catch that sexy buzz. All you have to do is set out on an adventure, whatever that means to you.

Maybe you haven’t been out on a bike for a while. Why not grab your partner and hit a local trail? You will likely be surprised at how turned on he gets from your adventurous, can-do spirit. And she’ll likely be thrilled that you want to hit the outdoors, just the two of you.

Or how about riding ATVs across rough terrain? Nothing like having that big machine between your thighs to get your mind wandering. Roller coasters can get you in the zone too. Something about making it back to ground zero safe and sound that makes you feel ready for the next adventure — this one in the bedroom.

Climbing a rock wall can do the trick too. And if you’ve never done it or it scares you to the core, all the better. Sex is all about attitude. And it’s hard not to feel pretty cocky when you’ve gotten over a fear that has kept you grounded.

All that’s left to do is get out there.

1. Make a list. What sort of adventurous things have you always wanted to do but have been too scared to take on?

2. Pick one. Depending on where you live and whether you can travel, your choices may be somewhat limited. But I guarantee there’s something you can do that will challenge and excite you. What about that trampoline in your backyard?

3. Do the groundwork. Where can you go? Do you want to be close to home or far, far away to take on this challenge?

4. Set the stage. Invite your partner if you want to share the experience or go it alone so he or she can spend the afternoon in suspense wondering whether you’ll really do it.

5. Psych yourself up. Whatever it is, you can do it. Just keep thinking about how great the sex is going to be after you push your body and mind to its limits and send your adrenaline through the roof.

6. Go for it! Enjoy it. Being scared can be good for you. And be sure to enjoy all of the benefits when you’re back home safe and sound with your partner again.

The point is this. Most of us go through the day hardly looking up from our computer screens. It’s hard to feel sexy when you’ve been “cubed” all day. Our bodies need to stretch and so do our minds. Physical challenges and adventures are the perfect fit for that, whatever your level of fear or fitness, wherever your geographic location.

Leap into the unknown. Stretch out your arms and your legs and your spine. Open yourself up to something you’ve hidden from. You will be amazed at how much you’ll want to attack your partner once you’ve attacked your own fears.

Jenny Block is a freelance writer based in Dallas, Texas. She is the author of "Open: Love, Sex, and Life in an Open Marriage." Her work appears in "One Big Happy Family" edited by Rebecca Walker and "It’s a Girl: Women Writers on Raising Daughters" edited by Andrea Buchanan. Visit her Web site at www.jennyonthepage.com.