The backstory for me is I knew 3 guys who died of sudden heart attacks in their 30s. One was an elite triathlete who had ridden on Lance's Tour de France teams. He was 36 and had 5 kids. Another was 38 and he had his heart attack on Christmas morning on the couch with his two young daughters and wife.
So my wife and I held healthy eating groups at our house each week and watched prominent cardiologist lectures together on the TV, etc. Together we knew of roughly a dozen aging parents who had heart disease and we tried to evangelize them. About 6 of them fully embraced the plan to eat whole plants and they are all doing great, even the 90-year-old.
Another 6ish said it wasn't for them and they continued with their health problems. 4ish have died, 3 too young. One just died a couple months ago, but although he enjoyed meat with most meals, he was slender and 95, in decent health until the end.
But I have to admit we've slowed down our evangelism because when we were new to it and naive, we thought we had found this great thing and everyone should know, so we were those zealots people hate. The thing is, people who embraced it were so appreciative and felt we had helped change their lives, but the uncomfortableness it introduced in times when people didn't want to hear about it cooled our jets. I'm not blaming them, we just didn't want to lose friendships.