I'm dizzy, light-headed, over-heated and just plain worn out after my workout this morning. Why? Because I overdid it.

I've been so focused on running from cancer by eating right and strenuously exercising -- research says it take five hours of vigorous exercise per week to keep breast cancer away -- that I drove myself to depletion this morning. It hit me when a wave of dizziness came over me in the midst of my outdoor workout. My body felt heavy, my strength disappeared, and it took every ounce of energy I could muster to put one foot in front of the other so I could get home. I suspect it was a combination of dehydration -- I didn't take water with me -- and heat -- it's really hot here in Florida -- and pushing myself too hard. The fact that I feel a bit under the weather didn't help either, I'm sure.

My body spoke to me today. And it's got my attention.

I'm trying to keep breast cancer away. I've had it once, and I really don't want it again. So I am committing myself to all strategies for keeping the disease out of my life -- like eating right, maintaining a normal weight, not drinking, not smoking, and as of yesterday, exercising strenuously.

New research shows strenuous exercise is what it takes to minimize the risk of breast cancer. Not moderate. Strenuous.

OK, I'm on board.

Now I've been a student of moderate fitness for most of my life. But now I'm embracing this new approach, this new way of pushing my body to its near limits. I figure if my choice is cancer or strenuous exercise, I better take the route that will leave me sweating and huffing and puffing, not sick and weak and bald. And so yesterday I took my first stab at what I will try to do at least five hours per week -- what experts say it takes to make a difference.

It all started with a warm-up lap on my treadmill -- just one lap at 4.5 miles per hour. Then I upped my speed to 5.3 and ran for a mile and a half. I continued running for another half mile at 6 miles per hour and then began walking again. I started at incline 1 for one minute, then moved to incline 2 for one minute, then incline 3 for one minute, and so on until I reached incline 10. My goal was to then continue walking while decreasing the incline each minute for ten minutes -- but I was so out of breath and fatigued, I jumped the incline down to 4 for one minute, then did 3 for one minute, 2 for one minute, 1 for one minute, and then I stopped. The whole process took about 40 minutes and left me soaked with sweat and gasping for air. Then, just in case my workout wasn't strenuous enough, I did 20 push-ups, a handful of sit-ups, and a few other floor exercises before heading to the shower.

So that's my version of strenuous. Now, I don't plan to do this same exact routine for all five hours I must complete each week, but I do intend to sweat and huff and puff just as much as I did yesterday. Because if strenuous is what it takes to ward off evil cancer cells, then I'm game.

I just ran three miles on my treadmill. I have never been the athletic one in my family. My sister is the one who was born with the athletic streak -- she played softball and lettered in tennis after giving the sport a try with no previous experience and may have helped her high school basketball team win a state championship if it weren't for the major knee injury she suffered just before the big game. I, on the other hand, was born with a streak that has something to do with hair, nails, and lots of shoes. I was never interested in sports, gym shorts, or sweating -- which is what makes running three miles a big deal for me.

I wish I had started running long ago -- because I really like it. I like the loud music that pumps through my MP3 player and the change in my cadence as each new song begins. I like the motivation of knowing I'm pushing my body and accomplishing a physical challenge. I like that my endurance improves with each mile I travel. I like the mental release and the thoughts that run through my head and the cleansing effect I get from running. And I like sweating.

It's possible running would not have appealed to me long ago, even if I had given it a try -- because times were different long ago. I was healthy. I was happy. And I had no reason to marvel at the possibilities of my body. Without a natural impulse for physical fitness and challenge, I was completely satisfied with the status quo. But now I have an acquired impulse -- because cancer has threatened the very body I once took for granted. And I want it to be strong. I want it to be healthy. I want it to stand up to any possible threat. So I run. And when I am not running, I look forward to running.

In just a few weeks, I will run in the 5K Making Strides for Breast Cancer event with my athletic sister. I will run by her side. With my loud music for motivation. With the inspiration that I am making a difference for my body and for women everywhere. With my gym shorts on. And a ball cap covering my hair. With sweat dripping down my face. I can't imagine a better feeling.