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.

Environment Canada meteorologists are warning people who enjoy spending time in the sun to do less so this year. As the ozone layer continues to thin, the danger for sunburn, cataracts and skin cancer continues to increase. The ozone layer is not protecting us from the sun's harmful ultraviolet radiation as much as it once did.

According to Environment Canada, the ozone layer across Canada has decreased by four to eight per cent over winter and spring, and the more sunny days there during the summer season, the more skin cancer risk to those who spend time outdoors.

Counting on sunscreen lotion to protect from the damaging rays of the bright day sun is no longer sufficient. Skin cancer experts insist, to be safe, stay out of the sun from 10 a.m. to 4 p.m. -- if you must be outside -- stay in the shade. Wear a wide-brimmed hat and quality sunglasses that offer protection from UVA and UVB radiation, and a long-sleeved shirt. Gone are the care-free days of walking out the door in shorts and a summer top, to spend the day enjoying the warmth and brightness of a summer day. Or, for sun worshippers, a day basking in the sun to achieve the golden tan.