A bash function I use to force me to do pushups every 30 minutes throughout the work day.

work.sh

work() {
    while true; do
      sleep 1800 #30 min
      espeak "$1 pushups"
      xinput set-prop 14 'Device Enabled' 0 #disable keyboard
      xinput set-prop 16 'Device Enabled' 0 #disable mouse
      xset dpms force off #disable monitors
      sleep 15
      xinput set-prop 14 'Device Enabled' 1
      xinput set-prop 16 'Device Enabled' 1
      xset dpms force on
    done
}