These youthful experiences vacillated from a the first stepping stone to a career as a musician, to you cringe whenever you see the instrument you played. Chances are, the answer lies somewhere in the middle. You played well enough to sound pretty good. Or, your public performances consisted of Mom or Dad forcing you upon unsuspecting dinner guests. In any event, now that you're a Grandboomer, playing a musical instrument may be something you want to return to.
Any instrument is great for manual dexterity, and all provide some degree of exercise.
The health factor aside, what you may find is that the beats and sounds that escaped you as a youth, are now easier to perceive as an adult. Recently, after a basement search, my spouse was delighted to find her old music books. It was a journey that had been stimulated when I purchased a portable pump organ at a local antique store. The instrument only has about a third of the keyboard, but my wife was delighted and started playing tunes from memory. Armed with her music, she has since started playing in earnest again only to be frustrated by the lack of keys.