So the beta version of Minecraft 1.8 is officially out and you want to explore the new worlds and features of the pre-release. The best way to explore is to move around super quick right? So take a look at this walkthrough on sprinting and flying in Minecraft 1.8.
The key commands are:
Sprinting: Hit the W key twice, then hold it down.
Flying: Hit the space key twice and hold to fly up and the shift key to go down.