Arm strength & 70-year old reminders

In the last two weeks I have had the unusual experience of being active in the care of my 70 year old father and my 70 year old mother-in-law.  It is through this experience that I am so incredible grateful for the genetic code that my parents have passed down to me.  About 6 weeks ago, my dad injured his knee while dodging a wave during a spontaneous walk on the beach.  He is a fabulous physical specimen of preventative health and fitness.  He bikes, kayaks, travels all over the world, and walks regularly with my mom (who is herself a youthful 67).  My mother-in-law on the other hand is on the other end of the spectrum.  She has many chronic health conditions and after a series of recent health issues, we are preparing to move her in to an assisted care residence.  I stayed with her last night to help with some mobility issues she was having.  Earlier in the month I watched my dad easily maneuver with a walker and later crutches - his upper extremity able to carry a heavier load while he recovers from knee surgery.  My mother-in-law, on the other hand, struggles to push herself up into her walker.  These wonderful object lessons so closely together have encouraged me to add a push-up routine to my daily activities so that I can maintain a strong upper body to go with my increasingly strong lower body.