I can empathize with your dad, as I hate exercise as well, even while liking the benefits. I hate treadmills, jogging, ab work, etc… Fortunately, I do not consider lifting to be exercise (yes, technically it is). I want to be stronger, first, and bigger, as a side. Lifting is a means to an end. Also, it is a GREAT stress reliever. It also gives me a great sense of achievement, which has obvious benefits.
If you could find a way to get him involved without labeling it strictly as exercise, it might be easier.
Maybe approach it from the angle of creating time for the two of you to do something together. Something that also carries the side benefit of giving you more, and better, years.
Also, go easy into it. No need to jump straight into something that wipes him out and puts out the fire. If he is like most folks, after doing it for a while, it will become habitual. take your time working into something that yields benefits he needs.
Yo Momma has some great ideas…scheduling it around him, and with him, will help keep him at it once on your way. Also, make the goals. It gives a sense of accomplishment and as you work towards your own goals, it gives him an active part, especially if you are able to workout with him. I know that I can’t wait for my kids to get to an age where they can workout with me.
If you need a little more push, you can do what I did with my mom…tell him that it would be nice if, when the time comes, he is healthy and strong enough to be able to pickup and hold his grandkids.