I have an app I built for myself (because I couldn't find anything appropriate) to ask me questions via notifications like rating how I feel, how's my sleep, am I alert, eating well etc. its probablistic both in when it alerts and what it asks and I power a self monitoring dashboard off the back of it.

There were two key insights for me:

- too frequent or predictable and I'll ignore it

- always being reminded about something negative is bad for you

You didn't give a lot of information in your question; so that is my two cents.