Recently, I visited my brother-in-law whom I was told is not well.  He's married to my older sister.
When my wife and I arrived at his house, he cheerfully greeted us - obviously happy that they have
visitors.  When I asked him on his health, he complained that both his knees are very weak, he can
hardly walk, stopping and taking a rest after walking a few steps.  "Old age" says he.  I disagree.
I told him that I regularly participate in 10 km runs and in one particular run, there was an 80 year-old
man who regularly participate in 10 km races.  He just kept quiet.
I frankly told him that we have to work hard for our health. And this means doing physical exercises
and sweat it out.  The muscles need to be exercised - "use it or lose it" is the maxim.
I feel sad for him - for the word exercise is not in his vocabulary, completely alien to him.
At 74, I walk/jog for 4 to 5 km every morning and followed by light barbells and dumbells when
I reached home.  I'll continue my exercise routine with floor press, sit-ups and shadow-boxing
and shadow-fencing.  After working out a good sweat, I'll have my bath.  I feel invigorated
and loved every moment of it.