There are lots of unproductive pleasures to explore, when one is no longer interesting you can move to another.
Incidentally, one of the unproductive pleasure is starting side projects. The pleasure is immense when you spend few hours setting up yet another Clojure/Haskell/whatever project. This time it definitely is the one you are going to see through to finish!
My wife tells me this all the time - because I am on the spectrum I see things in black or white; work vs fun, productive vs unproductive. Only black or white. I think I'm starting to understand...
The key is moderation. Don't dedicate 100% to productive-only tasks or you'll burn out. Don't dedicate 100% to veging on the couch watching TV or you'll bore out.
Can't everyone just stop analyzing every minute detail of life and just chill by living in the moment?
Spending a few decades thinking about the meaning of life might be considered unproductive - or it could be considered "being a philosopher". (Most) art is arguably fundamentally "unproductive". I suppose one might say that if you, over time, don't impart some impact on the people around you (share a work of art, pass on wisdom, [ed:raise] (and/or) feed a child...) then you've been "unproductive".
But are you a philosopher by virtue of achieving enlightenment or by virtue of helping others achieve enlightenment? If you died before you came to a crucial insight -- was your time spent thinking up to that point "unproductive"?