We all tend to slouch in our chairs now and again, and for some people, that means back problems. If you're sick of slouching all the time, Adafruit has put together a slouch detector that sets off an alarm when your posture is failing.
The idea here is to build a little wearable that sits in your pocket, and when you slouch, it beeps at you. It's a simple little device, but if you find yourself slouching a lot, it might be exactly what you need to improve your behaviour. The device itself is made with a Circuit Playground, some batteries, a pin and a few lines of code. You'll find everything you need over on Adafruit.
Circuit Playground Slouch Detector [Adafruit]