Your skeletal system breaks many rules of architecture. The 22 fused skull bones, providing a crash helmet for your brain, make your skeleton top heavy. The entire skeletal structure balances on a few square inches of bone at the bottom of your feet. Even with these design challenges, the structure of your bones accomplishes amazing feats of engineering. The skeleton is extremely light providing agility, while also providing amazing strength. The design of the lower limb bones allows your center of gravity to remain above your hips allowing smooth walking as opposed to a side to side gait exhibited in other animals. This along with highly responsive sensory organs and an advanced brain make it easy to balance on a few square inches of bone.
Each bone is composed of struts and arches with spaces in between. The spaces make the bones light. The struts and arches are arranged to direct stress to the strongest areas of the bone. The Eiffel tower is designed the same way, as it stands on 2 feet and its struts direct stress to the iron legs where it holds the most strength. Any shock or stress applied to the bone causes a layer of liquid bone to form where its needed while those parts that don't receive stress are dissolved by bone destroying cells. The nutrients of the dissolved bone material can then be recycled in order to strengthen the bone where it needs it most. This is how weight-bearing exercise strengthens bone, while sedentary behavior weakens it.
Some of the bones, like the cranium are made up of many smaller fused bones. However, we won't get carried away with details. Here's a good start.
Bones are the framework that will support every pound of your body for the rest of your life. Developing good habits now will help you get through periods of old age that can be real problems for bones.
Add calcium regularly. You need to consume about 1000mg of calcium per day. Most people are lacking about 250mg of calcium per day. You can make up the difference with one 8oz. glass of skim milk per day, which provides about 350 mg of calcium. If you can't stand the stuff or are lactose intolerant, try milk substitutes or calcium rich juice. For most of you, the majority of your day is not spent doing physical labor, so the best way to ensure strong bones is to regularly lift weights. Other weight bearing activities, such as walking, running, tennis or basketball, help strengthen bone as well. A full body weight lifting workout strengthens bone, while aerobic exercise primarily serve to maintain existing bone. Make sure to target the hips and back within your full body weight lifting workout, since these areas are most vulnerable to bone loss. Wear comfortable, well-supported, well-fitted, well-made shoes, and when they look like they've been through hell and back, replace them with new ones. Girls, those high heal torture devices you call shoes should not be your every day shoes. Tight fitting shoes can cause ugly and sometimes painful corns, bunions and other painful foot conditions.