Climbing a mountain is no easy feat, but what if that mountain is actually the floor? That's the concept of this week's exercise which asks the question: What happens when you get on the floor and run your knees in and out as fast as you can? The obvious follow up to that is to wonder why someone would want to do this and the answer to that is: Because you can (although, if you really can't, I have some variations below).

Mountain climbers are an excellent move for building cardio endurance while also building core strength and agility. This is also a great move when you don't have much (or any) equipment and want a challenging way to work your body.

There are a couple of ways to do this move. One, is to run the knees in and out without touching your toes to the floor. Another is to do the opposite and touch your toes to the floor, making it more of a foot-switch than a run. If this move doesn't agree with you, you can take it slow and simply walk one foot forward into a low lunge, walk it back and switch legs. I also have a gliding disc version that might work for people who need less impact.

Work this into your usual cardio routine or add it to other cardio exercises to make your own high intensity circuit workout.

Do it right: Begin in a pushup position on the hands and toes. Bring the right knee in towards the chest, resting the foot on the floor. Jump up and switch feet in the air, bringing the left foot in and the right foot back. You can also run the knees in and out rather than touching the toes to the floor. Continue alternating the feet as fast as you safely can for 30-60 seconds.

The battle between cardio and strength training, at least the battle that exists in our minds, has been going on for decades. The two actually get along quite well on their own, but add a human to the mix and that's where the conflict comes in.

Whether it's buried somewhere in your genetic code, the type of muscle fibers you have, what you grew up doing, age, gender, experience or all of the above, most of us have one activity we like (or at least tolerate) and one we do because we're supposed to.

There's no doubt you need both to lose weight and get fit but many of us, if given a choice, would easily give up our least favorite if we could get away with it.

While cardio and strength training can overlap, thinking of the differences between them, it's easy to see why some of us would prefer one over the other. With cardio, there's the endurance factor: Breathing hard, sweating, having to sustain a certain level of discomfort for, sometimes, long periods of time. For some? This can feel like torture. For others, there's nothing better than a long cardio workout to blow some stink off.

With strength training, you have the burn factor: After a few reps, providing you have enough weight, a burning sensation starts deep in the muscles and, the longer you lift, the worse it gets. For some people, this can feel like torture, while others love focusing on their muscles, feeling them contract, imagining them getting stronger.

Thinking about your workouts, about the differences between cardio and strength training, which one do you prefer? Would you happily give up one over the other? Or perhaps you like them both in certain ways? Vote in this week's poll and tell us what you think about cardio and strength training.

We're often so ready for spring to get here that we forget one important thing: Our bodies often aren't ready for it. It's not just the extra activity that can cause problems (like the general feeling that our bodies grew muscles we've never had before), but it's other things that sneak up on us like allergies, drawers full of workout clothes that stink/don't fit/have holes in them and the variable weather - Warm and sunny one day, cold and rainy the next.

I've got a couple of resources to help with the soreness and allergies:

• Exercising With Allergies - The American College of Sports Medicine offers some basic tips for exercising during allergy season. Here's one I didn't know: Breathe through your nose as much as you can when you exercise because "The nasal passages act as natural filters and humidifiers." Guess you want to avoid sprints on a bad allergy day.
• Preventing Sports Injuries - It's easy to overdo it this time of year. In fact, I've already had two clients out with back injuries from overzealous gardening. Our Sports Medicine Guide offers some tips to avoid that and you might want to think about working on your flexibility and core strength if you'll be doing a lot of yard work. Marie, our Guide to Gardening, also offers some great exercises for gardeners.

I can't do anything about the weather (except complain about it, which I do incessantly), but I do have an updated list of Spring Fitness Essentials, which can help you update your wardrobe to accommodate crazy spring weather with top picks for clothes, shoes, socks and other top picks for both men and women.

Exercising at home has a few advantages. One is the ability to put on your workout clothes and walk a few feet to your workout space, which is much simpler than driving all the way to the gym.

Also, you can do all kinds of things at home that you can't do at the gym - Watch movies on your big screen TV, listen to your music as loud as you want (even sign to it, if you're so inclined) and do pushups with your cat or dog 'helping' (read: Sprawling under your face or crouching on your back, beyond excited that you've come down to the floor to play with them)...something frowned upon at the gym.

There are some disadvantages too - Motivating yourself to exercise instead of doing other chores or tasks, lack of equipment variety and, of course, the fact that your (soft, warm, cozy) bed is located so close to your (stark, cold, exercisey) home gym, that you often find it hard to traverse that small distance.

Another tough one is figuring out how to get in your cardio.

This is a no-brainer if you have cardio machines or like to go outside, but, if you don't, you may find this a real challenge.

There are some options, of course: Exercise videos or movements that require no space and very little equipment like jumping jacks, jump rope, walking/jogging in place and the overhead cat toss (not recommended for the inexperienced exerciser...or cat). The problem with those exercises is that they're not as sustainable as, say, getting on an elliptical or going for a walk or run. You can only run in place or do jumping jacks for so long before you either get too winded or too bored.

What may work for you in this situation is to choose 10 or so cardio movements (check out these 10 minute timesaver workouts for more ideas), and doing each for 60 seconds, taking walking breaks in between as needed. You can complete 1 or more circuits, putting together the perfect cardio workout for you.

That's just one option and I've got a few more, if you need some ideas:

Home Cardio Resources

• Step by Step - Home Cardio Exercises
• Advanced Cardio Blast Workout
• Step by Step - Low Impact Cardio Exercises
• Low Impact Cardio Challenge
• Jump Rope Circuit
• Boot Camp Workout

What about you? What's your favorite way to do cardio at home? Do you use machines, videos or do you have go-to exercises to make your own workouts? Leave a comment and tell us about your home cardio workouts.