Have a heart attack, have a stroke, develop diabetes and High BP have bypass surgery..........anyone of those should motivate you to go to the Gym......or better still swimming pool,
It's called willpower in my case, I'm 63, I still workout 3 times a week, often I really don't want to do it, but I apply the same willpower to doing it that won me my Green Beret years ago, it works for me, and bottom line is I appreciate the benefits of doing it afterwards!
Good luck!