For a related tangential idea to "mindset you can't change willfully", think of a continuum along two axis, one of addiction/habit vs mere temporal coincidence and the other axis of fix it yourself vs professional intervention. Maybe a third axis of success rate! And a fourth axis of success of introspection/interpretation something like (reality) - (the victims observation).

Another fun related tangent is the article examples were very pedestrian and conventional, I wonder what the article readers would think about old dudes at a SCA event or a civil war re-enactor event. Or a star trek convention. Or a Renaissance Faire.

In the sense that the participants in the first study had their whole surroundings changed and molded in order for them to live in the past; yeah, most of us can't really use that as a viable strategy for feeling younger.

As far as a mindset in itself though, is changing your mindset something that is impossible? Most of us don't even really make an effort at all, so I tend to think of it as a largely uninvestigated area (as far as most people are concerned).