Pick something that'll make you smile and do it. Then find something else and do that too! Throw in something that you've never done but have always want to do and then do that! For me it was going to Wembley Stadium in London last September to see Coldplay before my ears can't take the loud noise (damned Aerosmith, Alice Cooper, Yes, Rolling Stones and Led Zeppelin concerts in the 70's and 80's did in my hearing!).
I was shocked how quickly I went from being 18 to 25......30 to 40.....50!!!! Time passes was too damned fast and it'll only become more difficult to do certain things as you grow older. Hate being melancholy but by the time you're in your 50's you'd better have put a line thru (1) bungee jump from a high bridge in Iceland; (2) run the Colorado rapids with friends; (3) hurl yourself from a plane and pull the parachute cord after a nice freefall; (4) have a 3some and a 4some; (5) rapel down a cliff face; (6) dance like an idiot at the best club in town; (7) take a cigarette boat out from The Keys and feel the wind hitting you at 100+ mph while heading for Cuba; (8) scuba dive in Aruba; and (9) climb into a shark cage and watch the monsters off of S. Africa. There's more for others but it's nice to look back and know that you've done some things that make you smile and shudder (goddam how'd I ever survive doing THAT!).