Welcome to the forums. You're not crazy; I'll be 63 in a couple of months, too. I don't intend to stop any time soon.

You will want to talk to your cardiologist before you get started, and see what he thinks of your plan. Start slow in easy country, and work your way up.

You may want to carry as light a pack as possible. There are a lot of good threads on that - the main strategy seems to be to define "necessity" pretty narrowly, and only take what is necessary to be warm, dry, hydrated, and well-fed on the trail. A supporting tactic is outfitting yourself with good, lightweight gear. If you want to start a feeding frenzy, just post your gear list here and ask for advice about it.

It's great to add another hiker to the fold. Good luck, and good hiking.