Stress the importance of the different types of pressure our mind and body experience in a lesson about how certain types of stress are actually necessary and good for our bodies. As astronauts and people with injuries can attest, not using muscles for even a short period of time can cause them to shrink and can also weaken bones. Give your class a simple conditioning activity to do every other day over two weeks; as they track their data, they should see that regular use of muscles, even in small amounts, builds stamina and strength. Tip: The extension activity should be completed as part of the lesson; it incorporates graphing, which reaches both Common Core math standards and Next Generation Science Standards.