When grandpa tells you what he’d do differently, he’s handing you a map he paid for.

Regret said out loud is useful information somebody else paid full price for. When an older person tells you what they would change, they are describing a route they walked and would not walk again, which is precisely the kind of knowledge your own experience cannot deliver in time to be any use.

Ask one older person what they would do differently, and ask what it cost rather than only what it was. Then take the single part that applies to you right now. Most advice is too general to act on, and this sort arrives with the receipts attached.