As for guitar it’s going to be a lot of uncomfortable hand positions and repetition and muscle memory. I played five years ago. I could play 20 songs in a row. Now I get tired after 2 songs. My fingers. I need to build up the callouses again.It's never too late to learn an instrument.
I know a guy who taught himself how to play the banjo at 70 one who taught himself how to play the Native American flute at 60 and many more.
I also need to learn new songs. I already have five. I don’t even want to play the songs I played five years ago but even if I did I’ve forgotten 90% of them.