I watched the simpsons this week (S28e07), where grandpa has a "cubagasm"...
Part of this scene (not in the clip) is a reference to Professor Ellen Langer and studies on aging. http://www.nytimes.com/2014/10/26/magazine/what-if-age-is-nothing-but-a-mind-set.html
For me it's comics, guitars and music. I do have my first bass still (24 years later!), but I figured I don't need the exact instrument - I just need an instrument and some time to play some of those 'old' tunes. The Doors, The Beatles, Slayer, Metallica, Megadeth - all the stuff I learnt when starting out.
Does it work? My older brother made a comment a while ago, I'm 40 going on 14 - and that I directly ascribe to music and playing an instrument.
So pick up yer axe and rock out favourites from your youth...It ain't nostalgia, it's medicinal