Thanks for the introduction! As a fellow seventy-year-old, I'd say you're wise to hold beginner mind. I started piano going on four years ago (no teacher) and went back to foundations (with a teacher) a year and a half ago. That was a good decision. I bought my acoustic guitar a few months ago with very simple expectations (strum and sing). The main challenge has been growing calluses. I'm up to 25 minutes of practice a day and now that I have baby callused patches I can fret a bit more cleanly. I think that's your challenge, too.