Trekkie..I like to think there is hope for all people and don't give up...Sure,not everyone likes the same activities..But,you find a way to get through to him , with patience,etc.;maybe you can mold him into a better person..
Learning to ride is like graduating from Vouvray white wine to Cabernet Sauvignon..Gradual...
Not everyone wants to intentionally be a slobby couch potato...I would influence those worth influencing; by easy fun rides..Easy rides, don't need the advanced kit for enduring 100 milers...
Favorite scenic rides..It just might get to him...Probably, riding off road in baggies is the best start...Once he gets in 20 miles he might see that saddles cause friction..But, 20 miles of scenery under your own power gets to ALL? Maybe, this clod isn't worth the time?
Next step, maybe see what kind of reading he doesn't do..