sometimes I push too hard and get tired and there's no one there to encourage me and if I talk to myself people look at me.
So get a computer and heart rate strap and/or power meter.
When the display shows slacking off ride harder. Some computers can be configured to beep at you when that's not enough.
When you're going too hard for your training plan that day ease off so you're fresh enough to ride hard enough on your tough days even when that's embarrassing slow and you're being passed by kindergartners on big wheels.
It's simple although not always pleasant. Just 18 minutes out of 20? oww...