New Delhi, May 17 -- My uncle is 65. He plays football twice a week, pickleball twice a week, swims thrice a week, cycles from time to time and walks for about 30 minutes every single day. He also walks and takes public transport to the college to deliver lectures or meet friends. But he refuses to go to the gym despite knowing that he needs more muscle to maintain a good quality of life as he grows older.

For now, his solution is having a protein shake after playing sports or swimming. On the metro ride home after a game in mid-April, he says, "My cardiovascular health is up to the mark. I need to do something about my muscle mass, but I really don't like the gym and weights. Can you show me some body-weight exercises that can help me b...