Repositories are awesome, and we should have more of them.
I recently completed BJ Fogg's Tiny Habits, and it's a pretty lightweight way to install new habits (recommended). However, I realized I could use a better repository of useful habits.
So, please use this thread to suggest habits that you've found useful. Bonus points for evidence/anecdata of usefulness.
Obviously, 1 habit per comment makes upvotes a clearer signal of collective approval.
Be aware, though, that putting heavy things regularly in men's jacket pockets - especially the inside chest pockets - will tend, over time, to spoil the 'line' of the jacket and make it look much less smart.
(Some people may not care about that, but it's worth considering - see e.g this response to this post.)