I have formed a habit of walking once a day, almost everyday.  In Taipei my wife and I would take a walk in sunny afternoons at Bihu Park or Dahu Park before dinner.  Usually I did fast walking for forty minutes, while my wife walked thirty minutes in moderate speed, and then we met at the gate of the park or the subway station. 

Here in Bay Area, we do the walking along the sidewalks of the community for thirty minutes each time.  Unlike in Taipei, we walk side by side with same speed.  In order to draw abreast with her, I started to walk on tiptoes so as to lower my speed.  Obviously, walking on tiptoes can strengthen our muscles on calves and thighs, which are the props for our bodies, especially for seniors.  (But I am not sure if such a practice would bring adverse effects on my knees.) 

Attached below is a reportage about the benefits out of standing or walking on tiptoes.

https://www.toutiao.com/a6727893816482726408/