I'm not 65 (yet, but close), I'm not retired (yet, but close), I do not have grandkids at your age or in your position (yet
) but my son has nailed some good things for me @ Christmas and birthdays. Very memorable times spent fishing with him on a few guided trips. The first one was literally a bust but we had a great time and many, many priceless memories despite no fish caught. Ones after that were only better because we did some catching.
A couple of trips were not even a "high priority" for me but I find all fishing great fun and I'm always up for an adventure. Time with my son? Well, let's not let the MasterCard folks get hold of any video of our trips...
Give your Granddad some memories and share the experience.
Edit:spelling