> "Cron is one of Linux’s most useful tools and a developer favorite because it allows you to run automated commands at specific periods, dates, and intervals using both general-purpose and task-specific scripts. Given that description, you can imagine how system admins use it to automate backup tasks, directory cleaning, notifications, etc."
For example, one could get a cheap Raspberry Pi, set it up as a server on your local network, and use cron to have it send your phone daily email alerts about taking care of yourself on a particular schedule. Hmmm FOSS project?
[Edit re OP question: I wouldn't use pre-packaged apps for this because of the motivation issue. If I build something myself I'm far more likely to use it, because I want some kind of payoff for that original input of effort.]