Your familly is growing. Work is stressful. And it gets harder and harder to hit the gym. Its when we hit the age of forty is when we really begin to see our bodies begin to change, again. Above the surface it may seem that there is no significant change, but underneath there are some dramatic changes. Below are some facts from Inside the Living Body explaining some of the changes.

• By our mid- to late 40s, our skin begins to lose elasticity, becoming saggy and wrinkled. Years of exposure to the ultraviolet rays of the sun have worn down the collagen that binds our skin cells together. We do not regenerate the cells as quickly anymore.

• Our eyesight is also not the same. The inner lens cells — the same ones we were born with — stiffen and don’t focus light as well. The lens cells, heart cells and some brain cells are the only ones our body never replaces.

• Even though we may exercise, our body shape changes. We lose around 6½ lbs. of muscle each decade of our adult life — and put on more fat. Women tend to put fat on their hips, men around their waist.

• But fat is much more than an extra inch around the waist. Bright yellow fat deposits find their way into every available cavity within our body, even inside our blood vessels. In extreme cases, the fat builds up so much that it blocks the vessels completely, causing heart disease — the leading cause of death in the western world.

• The stress of working and raising families causes premature aging of the cardiovascular system. The outward signs include sweaty palms, shortness of breath and dizziness. Inside the body, adrenalin and cortisol flood the bloodstream, our heart pumps faster and our muscles and arteries contract.

• Stress accelerates the aging of our blood vessels. High blood pressure damages cells in the artery walls and they become stiff and thick, especially in our biggest artery — the aorta. Arteries with stiff walls restrict blood flow. That means as our blood pressure rises, our heart works harder. It’s a vicious circle — the more we get stressed, the more we damage our blood vessels, and the more we damage our blood vessels, the less able we are to deal with the effects of stress.

• For women, menopause triggers a dramatic chain reaction in the body. Eggs or the hormones estrogen and progesterone are no longer produced, and as a result, women suffer from insomnia and hot flashes.

• In our lungs, shallower alveoli (air sacs) mean we’re more easily out of breath.

• Our brains have shrunk by 10 percent, which could explain why some of us get confused and forgetful.

• We become hard of hearing — we can no longer hear quiet sounds because so many of the sensory hairs in our cochlea (inner ear) have been destroyed.

• Our once-clear eye lenses are now stiffer, turning a yellowish-brown color and even cloudy — as crystals form in the lenses — the result of a lifetime of exposure to the sun’s ultraviolet rays.

• Our skeleton is also dramatically affected by aging. Bone cells are destroyed by hormonal changes faster than new cells can be rebuilt. Our bones, therefore, are more brittle and we suffer from osteoporosis.

• Every day, cells clone themselves in the billions to battle wear and tear on our organs. The DNA inside each cell gets copied. The old cells die off and the new ones take their place. But the copying system isn’t perfect. Any imperfections in our DNA are also duplicated. Over a lifetime, we make so many copies of our cells that even the tiniest defects accumulate. It’s like using a photocopier. Copies made from copies degrade in quality. In our faces, we have totally replaced the bone every 10 years since we were born. Our 70-year-old face is a seventh-generation copy of our baby face. The imperfections are exaggerated with each copy.

• Another reason for aging might be the air we breathe. We need oxygen to live — but throughout our lives, it slowly poisons us. Inside each of our cells, our mitochondria are like tiny power plants, combining food with oxygen. They create the energy we need. But, just like a power plant, they also generate pollution. In this case, the pollutant is oxygen. The mitochondria change the molecules into unstable forms called free radicals. Over a lifetime, free radicals slowly suffocate the mitochondria and damage our cells.