I'm awake about 17 hours a day. Of those I'm being productive maybe 10 hours a day.
My working definition of productive is in the direction of: "things that I expect I will be glad I did once I've done them"[1].
Things that I personally find productive include
- Chores
- Work
- Eating
- Cooking
- Reading a good book
- Watching TV with my Wife/Kids
- Playing with the kids
- Socialising with friends
But not
- Doomscrolling
- Watching TV alone
- Playing most computer games
- Sitting on the couch doing nothing
- Reading a book I'm not particularly interested in
etc.
If we could find a magic pill which allowed me to do productive things 17 hours a day instead of 10 without any side effects, that would be approximately equally as valuable as a commensurate increase in life expectancy. Yet the first seems much easier to solve than the second - we already have some drugs which get pretty close (caffeine, amphetamines).[2]
Now obviously the correct thing to do is both, but in the same way as we want a Manhattan project for anti-aging, we should also advocate for a Manhattan project for focusing/willpower.
I like this definition because it allows 2 different routes toward improvement, which you'll probably need to mix to get the best results:
Increase time spent on the activities which are already on your "productive things" list. Taking this to the extreme would likely eliminate load-bearing forms of rest, and drastically increase burnout risks.
Improve recovery activities to bring them from "unproductive" to "productive". You hint at this with reading a good book making the "productive" list but reading a disappointing book falling into "unproductive".
The lowest-hanging fruit for me tend to be in (2): When I'm able to give myself an alternative activity that's equally easy but less regrettable compared to an "unproductive" habit, and notice when to do it, I can often get equivalent results for the function that the bad habit was serving.