My sincere condolences go out to his family. They should be assured that he passed doing what he truly loved. I certainly hope that if a heart attack is in my future, it won't be doing something like shoveling snow.
The only thing I can think to take from this for personal motivation, is that we should all take our fitness level seriously. I've started using an elliptical machine daily and plan to incorporate bicycle riding into my life again. It's been about 10 years since I've been active at that , and I miss it. Tragedies like this can happen to even to most physically fit, but it certainly doesn't hurt to be in SOME kind of physical shape - not to say he wasn't, I have no idea.
If (God forbid) any of you find me in the same condition someday, I can honestly say there are no regrets. Riding with you guys is a life-enriching experience.