I always hated the smoke and the way your hair and clothes would still reek of it the next morning. Now, on the rare occasions I catch a whiff of cigarette smoke, it's nostalgic and almost smells good.
This one is kinda life changing if your life isn't ruined by getting caught with a joint.
They don't really cover it, but one literally life changing one has been medicine; a lot of things that were a death sentence (and often a very nasty, slow, painful one) in the 90s are now quite treatable. Particularly cancers, but also there've been big improvements in cardiac treatment, and the treatment of certain diseases (particularly HIV).