How would I go about making my game loop in JME

I am using JME3 and i want to create a simple game loop. In other game engines, the whole program was a loop, but if i create a while loop that will loop forever… nothing gets rendered. I was thinking because the keyboard input for JME gets called automaticaly even if none of your code is looping I would create a binary keymap so 0 means down and 1 is up. I want to move the player paddle each time it loops but im just confused on where to start with the loop. I noticed there is already an update function for SimpleAplication so that confused me a bit. Thanks for any points!

jME3 already comes with a game loop.

See HelloMainLoop tutorial on how to use it.

Also, for your input question, you might want to take a look at HelloInput tutorial