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 think it's convincing that the effect, if it exists, is much smaller than the one for weight. The graph for weight is so obvious you don't even need to do statistics.