A few years ago, you’d only see someone talking into their phone if somebody was on the other side. Fast forward a bit and now talking to your phone when you aren’t on a call is no big deal. Siri for iPhone revolutionized the behavior, and nowadays it’s common to see people use their voice to control their phones. Luckily, these options are available on Android, too.
Siri only does what you tell it to do – it responds to direct questions, it doesn’t take the initiative and remind you of things itself. One good app for that is the free EasilyDo.