The process starts somewhere in your 30s. Cells begin to die off. Organs work a little less well. This raises your risk for certain diseases and disorders. But these changes aren't the same for everyone. Genes, lifestyle, and environment all play a role in how you'll feel during your twilight years.

With age, bones tend to shrink in size and density, weakening them and making them more susceptible to fracture. You might even become a bit shorter. Muscles generally lose strength, endurance and flexibility — factors that can affect your coordination, stability and balance.