Water

   Our  bodies are about 75% water. Not only does that mean that we need to stay hydrated but it also means that exercising in the water is beneficial as well. It is therapeutic and a great way to build core strength because of the resistance that water or a pool provides. Water buoyancy helps protect the joints and therefore allows you to strengthen them from that perspective. It reduces pain and increases flexibility, and it is also age defying.
   Think about it. The concept of time only exists because of the force of gravity. In the water gravity is as equally strong as gravitational force on land but in the water buoyancy is its own force and helps to offset the gravitational pull. This does not mean that you can be ageless by spending time in the water. :) But it is an age defying way to exercise!