Exactly this. You realize that your choices actually matter in the big picture. You have only so many years to work with, it becomes clear that some of the things in the “later” bucket will have to move to the “never” bucket. That makes you question things much more. Should I really go to the pub for the umpteenth time with my mates and lose my Sunday to a hangover? Oh I’d rather do something else and get a full Sunday! That’s only one example, but it is also a good one. You can try to make the most of your loss of invincibility and infinity and utilize that feeling to make better choices than in the past. No point dwelling on if those 10000 hours playing video games were well spent.