How to unlock your Mac just by walking up to it - There's no shortage of software that make the process for unlocking your Mac pc easier. There's Knock, which requires anyone to physically knock in your iOS device to unlock your Mac pc. Then there's KeyTouch, an app which utilizes Touch ID in your iOS device to unlock your Mac pc.
They still require you to interact on some level with another device, although both apps work. Neither is ideal, and not anywhere near as easy as Google's Smart Lock feature on Chromebooks.
Next, I felt Tether, thanks to a post on The Next Web. Tether is a combination of a free OS X and iOS app that leverages Bluetooth 4. Technology to monitor simply the only way close you are, or should I say iOS device is, to your Mac. When your device is within range (regarding 30 feet by my count), the app unlocks your Mac.
As soon as you walk away, your Mac is locked back up barring any unauthorized access.
Configuring it all set up is simple; download the Mac app from Tether's site. Then the iOS app from the App Store. Next, follow the instructions to connect your two devices.
A handful taps on your iOS device and a couple of clicks on your Mac later, you're all set up to walk away with peace of mind. Or at least the reassuring feeling of eliminating a redundant (granted, necessary) task in your life has just been eliminated. The team behind the app claims that updates and more features are on the way. I, for one, would love to see the ability to control the range of when an action is taken. Somewhere along the line of 10 feet would be more than enough.